Enterprise - SSD Form Factor Working Group.

Enterprise
SSD Form Factor
Version 1.0a
SSD Form Factor Version1_a.docx
December 12, 2012
Copyright © 2012 SSD Form Factor Work Group, All rights reserved.
Please send comments to Mark Myers
specification@ssdformfactor.org
Enterprise SSD Form Factor 1.0a
INTELLECTUAL PROPERTY DISCLAIMER
THIS SPECIFICATION IS PROVIDED “AS IS” WITH NO WARRANTIES WHATSOEVER INCLUDING
ANY WARRANTY OF MERCHANTABILITY, FITNESS FOR ANY PARTICULAR PURPOSE, OR ANY
WARRANTY OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION, OR SAMPLE.
NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL
PROPERTY RIGHTS IS GRANTED OR INTENDED HEREBY.
THE SSD FORM FACTOR WORK GROUP DISCLAIMS ALL LIABILITY, INCLUDING LIABILITY FOR
INFRINGEMENT OF PROPRIETARY RIGHTS, RELATING TO IMPLEMENTATION OF INFORMATION
IN THIS SPECIFICATION. THE SSD FORM FACTOR WORK GROUP DOES NOT WARRANT OR
REPRESENT THAT SUCH IMPLEMENTATION(S) WILL NOT INFRINGE SUCH RIGHTS.
The document revision is changed to 1.0a.
Changes are:
1. Changed 12V Tolerance to unspecified, and added an Implementation Note regarding power
tolerance. Leaves Max continuous current to 2.45A to match wider voltage range.
2. Changed text to show SFF-8639 as the approved normative document for mechanical
specification. Section 3 is now informative, not normative. There is still an overview and primary
drawings, but removed more detailed sections and reference SFF-8639. Specifically removed
sections on intermateability, layouts (footprints), and blind mate & wipe,
3. Changed pin numbers to match approved SFF-8639 (SFF-8639, 2012). Specifically E17-E39 are
relabeled S15-S28, E17-E25. No change in pin placement, aligning pin label with SFF-8630
(SFF-8630, 2012).
4. Changes to align with SFF-8630 (SAS Multilink). Removed references to SAS Multilink using
SMBus, 3.3Vaux, or Act2. These changes are only in pin list tables.
5. Added multiple Extended Capability enumeration fields to Section 9.2. This allows out of band
discovery of Dual Port support, RefClk extensions, SM-Bus Temp sensor, Active/Passive mode.
6. Added description to improve clarity, Section 2.6 and 2.7, added P-Init to Figure 29.
7. Editorial changes, including updating references and bibliography.
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Enterprise SSD Form Factor 1.0a
Table of Contents
1
OVERVIEW ................................................................................................................... 6
1.1
1.2
1.3
Overview ......................................................................................................................................... 6
Goals .............................................................................................................................................. 6
Technical Summary ........................................................................................................................ 6
1.3.1
1.4
1.5
2
SIGNAL LIST .............................................................................................................. 10
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
3
Electrical Channel ......................................................................................................................... 36
Presence and Interface Detect ..................................................................................................... 37
ePERst[1:0] ................................................................................................................................... 37
Power – 12V ................................................................................................................................. 37
Power 3.3Vaux ............................................................................................................................. 38
REFERENCES AND BIBLIOGRAPHY .................................................................................. 39
8.1
8.2
8.3
9
Simple Accesses to Vital Product Data (VPD) ............................................................................. 35
Extended SM-Bus management................................................................................................... 35
ELECTRICAL (POINTER TO OTHER SPECIFICATIONS) .......................................................... 36
7.1
7.2
7.3
7.4
7.5
8
Dual Port Mode (implications of DualPortEn#) ............................................................................. 34
SM-BUS OPERATION ................................................................................................... 35
6.1
6.2
7
Limit current inrush ....................................................................................................................... 28
Detecting Enterprise PCIe SSD Insertion/Removal ..................................................................... 29
PCIe Hardware and Reset System Requirements ....................................................................... 29
Software Implications of Hot Swap (Informative) ......................................................................... 31
DUAL PORT OPERATION ............................................................................................... 33
5.1
6
Connector Mechanical Drawing notes .......................................................................................... 17
Connector Plug Mechanical Drawings.......................................................................................... 17
Connector Plug Mechanical Drawings - Details ........................................................................... 19
Connector Receptacle Mechanical Drawings ............................................................................... 21
Cable Retention Mechanical Drawings ......................................................................................... 22
HOT PLUG AND REMOVAL ............................................................................................. 27
4.1
4.2
4.3
4.4
5
Signal Lists ................................................................................................................................... 10
Connector pin out ......................................................................................................................... 12
PRSNT# - Presence Detect and IfDet# - Interface Detect Signal Definition ................................ 14
DualPortEn# - PCIe Dual Port Enable .......................................................................................... 14
Reserved(WAKE#/OBFF#), Reserved(ClkReq#/DevSLP) ........................................................... 15
ePERst[1:0]# - PCIe Reset ........................................................................................................... 15
RefClk[1:0][+/-] – Enterprise PCIe Clocks .................................................................................... 15
Activity - Activity indication signal ................................................................................................ 15
CONNECTOR MECHANICAL............................................................................................ 16
3.1
3.2
3.3
3.4
3.5
4
Flexible Drive Backplane option .............................................................................................................7
Scope .............................................................................................................................................. 8
Outside of Scope ............................................................................................................................ 9
References ................................................................................................................................... 39
References Under Development .................................................................................................. 39
Formal Bibliography ...................................................................................................................... 39
SM-BUS - INFORMATIVE APPENDIX ................................................................................ 41
3
Enterprise SSD Form Factor 1.0a
9.1
SM-Bus Vital Product Data (VPD) ................................................................................................ 41
9.2
SM-Bus Enterprise SSD Capability Definitions ............................................................................ 42
9.2.3
SM-Bus Temperature Extended Capability. ............................................................................. 44
9.3
SM-Bus MCTP commands ........................................................................................................... 45
10
SYSTEM USAGE – INFORMATIVE APPENDIX .................................................................. 46
10.1
10.2
10.3
11
Pin usage across standards ...................................................................................................... 46
System Usage Examples .......................................................................................................... 50
Connector Keying (Informative) ................................................................................................ 52
SPECIFICATION CONVENTIONS ................................................................................... 54
11.1
11.1.1
11.1.2
11.1.3
11.1.4
11.1.5
11.1.6
11.2
11.2.1
11.2.2
11.2.3
11.2.4
11.2.5
11.2.6
11.2.7
Definitions ................................................................................................................................. 54
PCI Express® (PCIe) ........................................................................................................................... 54
PCI Express® Generation 2 (PCIe Gen2) ............................................................................................ 54
PCI Express® Generation 3 (PCIe Gen3) ............................................................................................ 54
PCI Express® x4 (PCIe x4) .................................................................................................................. 54
SFF standards ...................................................................................................................................... 54
SSD ...................................................................................................................................................... 54
Keywords .................................................................................................................................. 54
mandatory ............................................................................................................................................ 54
may ...................................................................................................................................................... 54
optional................................................................................................................................................. 54
R, RSVD ............................................................................................................................................... 54
reserved ............................................................................................................................................... 54
shall ...................................................................................................................................................... 55
should................................................................................................................................................... 55
4
Enterprise SSD Form Factor 1.0a
Table of Figures
Figure 1: Example configurations ...................................................................................................................................7
Figure 2: Flexible Backplane Implementation ................................................................................................................8
Figure 3: Signal List Summary (pin counts) ................................................................................................................. 10
Figure 4: Signal List Table (defining specification) ....................................................................................................... 11
Figure 5: Pin Out Drawing (Receptacle pin naming). ................................................................................................... 12
Figure 6: Drive type - Pin decoding .............................................................................................................................. 14
Figure 7: Connector Mechanical Overview .................................................................................................................. 16
Figure 8: Connector Examples ..................................................................................................................................... 16
Figure 9: Connector Plug Mechanical Drawing – Top View ......................................................................................... 17
Figure 10: Connector Plug Mechanical Drawing – Drive Insertion View ...................................................................... 17
Figure 11: Connector Plug Mechanical Drawing – Bottom View (outside of enclosure) ............................................... 18
Figure 12: Connector Plug Mechanical Drawing – End View (showing latch slot) ....................................................... 18
Figure 13: Connector Plug Mechanical Drawing – Detail A (key) ................................................................................. 19
Figure 14: Connector Plug Mechanical Drawing – Detail C (key pins) ......................................................................... 19
Figure 15: Connector Plug Mechanical Drawing – Detail B (Tongue) .......................................................................... 20
Figure 16: Connector Plug Mechanical Drawing – Section D-D (Tongue cross section).............................................. 20
Figure 17: Connector Plug Mechanical Drawing – Drive Keep-out Area ...................................................................... 21
Figure 18: Connector Receptacle Mechanical Drawing – Drive insertion view ............................................................ 21
Figure 19: Connector Receptacle Mechanical Drawing – Section E-E (Receptacle) ................................................... 22
Figure 21: Cable Retention Mechanical Drawing – Representative Cable Housing ..................................................... 24
Figure 22: Cable Release Clearance - Representative Cable Housing........................................................................ 25
Figure 23: Representative Cable Housing with flat ribbon cables ................................................................................ 26
Figure 24: Hot Plug Current Inrush Limiting ................................................................................................................. 28
Figure 25: System Reset Timing .................................................................................................................................. 30
Figure 26: Reset Timing Details (PCI SIG CEM, 2007) ................................................................................................ 31
Figure 27: Single Port and Dual Port example ............................................................................................................. 33
Figure 28: Typical SSD Form Factor Channel ............................................................................................................. 36
Figure 29: Power (12V) specifications.......................................................................................................................... 37
Figure 30: Power 3.3VAux specifications ..................................................................................................................... 38
Figure 31: SM Bus Vital Product Data.......................................................................................................................... 41
Figure 32: SM Bus Capability Definition ....................................................................................................................... 42
Figure 33: Dual Port Extended Capability Definition .............................................................................................. 42
Figure 34: RefClk Extended Capability Definition ................................................................................................... 43
Figure 35: SM Bus Temperature Extended Capability Definition ................................................................................. 44
Figure 36: Dual Port and Active/Passive Extended Capability Definition ............................................................ 45
Figure 37: Pin usage across Existing standards .......................................................................................................... 48
Figure 38: Pin usage across Emerging standards........................................................................................................ 49
Figure 39: Backplane for Enterprise SSD (PCIe x4), SATA & SATA Express (Client PCIe) ........................................ 50
Figure 40: Backplane for Enterprise SSD (PCIe x4), SAS & SATA.............................................................................. 51
Figure 41: Backplane for SAS X4, SAS & SATA .......................................................................................................... 51
Figure 42 Cross Standard Connector Keying ............................................................................................................... 53
5
Enterprise SSD Form Factor 1.0a
1 Overview
1.1
Overview
This specification defines the electrical and mechanical requirements for a PCI Express connection to the
existing standard 2.5” and 3.5” disk drive form factors. This is intended for PCIe connections to SSDs
(Solid State Drives) for the enterprise market of servers and storage systems. This provides a new PCIe
form factor that is storage friendly, leveraging both the existing PCIe specification and the existing 2.5”
and 3.5” drive mechanical specifications. This standard allows system designs that can support a flexible
mix of new enterprise PCI Express drives, and existing SAS and SATA drives.
Note: The References and Bibliography are listed at the end, in section 8 on page 39. The
Specification Conventions are listed at the end, in section 11 on page 54. This includes the standard
material such as the definition of “Shall”, “Should”, “May”, etc. and bibliographic material to reference
specifications. Also included are definitions of terms such as “PCIe”, “PCIe Gen 3”, “PCIe x4”, “SFF”, and
“SSD”. The bibliographic reference use the original author name, for example (SFF-8482, 2006) while
the section 8.3 give the current designator, for example EIA-966.
1.2
Goals
The following are the characteristics of the product envisioned using this specification:







1.3
1
PCIe connection to Enterprise Solid State Drives (SSDs).
Standardize connector and form factor – but enabling innovation using the PCIe model.
Fits in existing drive mechanical enclosures using a disk backplane. Supports both 2.5” drive
mechanical enclosures and 3.5” drive mechanical enclosures.
Support customer expectation for storage device:
o Externally accessible & Hot Swappable (with surprise removal)
o Support existing OEM’s existing drive infrastructure (device detection and indicators)
o Support existing OEM thermal architectures, and support for future enhancements.
Support for both single port (typical servers), or dual port (typically storage systems).
Meet projected system storage device performance requirements for systems introduced in the
2H 2011 to 2016 timeframe.
Enables flexible system designs that support Enterprise PCIe Express SSDs and SAS or SATA
drives using the same connector family, allow systems to support flexible mix of capacity (SAS or
SATA hard drives) or Enterprise PCIe SSDs.
Technical Summary
A technical summary of the “SSD Form Factor Working Group” is:





Focus is on connector which is supported in both the existing 2.5” and 3.5” form factors.
2
Supports the 2.5” drive (SFF-8223, 2006) specification unchanged, or supports the 3.5” drive
(SFF-8301, 2010) specification unchanged.
Compatible with existing SAS connector (SFF-8680, 2012). Meaning the connectors allow
interoperation, see Section 10. For example a new backplane receptacle would accept new or
existing drives. The connector is doubled sided extension to existing SAS connector. New pins
are 0.8mm pitch across the complete B-side and on top of SAS key.
Support for PCIe x4 (Gen2 and Gen3) signaling. References PCIe specifications for high speed
electrical specifications – unchanged.
The electrical channel is assumed to be similar to SAS-3 channel – short board trace, longer
cable, trace on storage backplane, SSD.
1
Definition of PCIe and reference specification are included in section 8 on page 40
Definition of SAS, SATA, SFF and reference specifications including official designations (EIA, ANSI,
INCITIS numbers) are included in section 8 on page 40
2
6
Enterprise SSD Form Factor 1.0a







25W connector limit, with 12V only delivery. Expecting Enterprise PCIe SSDs at range of power
levels, and expecting Enterprise PCIe SSDs to support software settable power limit, and
temperature monitoring.
There is optional support for 3.3V aux to allow probing device information before system power
on (Vital Product Data – VPD – over SM bus.)
Pins list is the merging of SATA/SAS signals and the PCIe x4 plus PCIe side band. The actual
high speed lanes for SAS and SATA are separate pins from the Enterprise PCIe pins. This
enables direct connection to SAS or SATA controller and separate pins to high performance
Enterprise PCIe upstream device without an intervening repeater, mux, or controller.
Support Single x4 or Dual x2 port as (2@x2) with dual PCIe side band
Supports Hot swap support details, basics same as SAS
Supports SM bus for out of band discovery
Supports PCIe power management features
Figure 1 shows example configurations.
Figure 1: Example configurations
Typical Server configuration
PCIe x4
(e.g. CPU x4
PCIe port)
conn
PCIe upstream
Connector
Disk Bay
Backplane
µC
2.5”
SSD Form Factor
Device
(Enterprise PCIe SSD)
Typical Storage configuration
Controller
conn
PCIe x2
Controller
Disk
Backplane
Connector
A
conn
PCIe x2
2.5”
SSD Form Factor
Device
(Enterprise PCIe SSD)
B
1.3.1
Flexible Drive Backplane option
The current technical direction allows for system implementations that support flexible storage backplane
bays supporting a mix of Enterprise PCIe or SAS or SATA or SATA Express devices. The system would
provide both a PCIe connection along with a separate connection to a SAS or SATA controller. The
system support infrastructure would also have to be extended to support the super-set capabilities (power
amperage, management signaling).
7
Enterprise SSD Form Factor 1.0a
The concept is that a single system or backplane design would support either Enterprise PCIe SSD or
SAS/SATA drives allowing an optimal balance of performance and/or capacity to be achieved. The
assumption is that SAS expanders allow adding SAS ports at low additional cost. This is shown in Figure
2.
The drawing of Flexible Backplane (Figure 2) is not the only implementation since a Hard Disk Drive
(HDD) optimized using just SAS/SATA and other implementations for just PCIe are also expected. There
are multiple variations of flexible backplane based on the capabilities of the supporting controllers. The
informative appendix, Section 10.2 on page 50, shows multiple other options.
The capability to build a flexible backplane is based on extending the existing SAS connector (SFF-8680,
2012) sharing functions like power and giving it the ability to meet SAS MultiLink (SFF-8630, 2012)
functionality as well as giving it the capability to deliver four ports of high speed PCIe. SFF-8630 does not
accommodate the additional 2 x PCIe ports nor does it provide the PCIe sidebands.
Figure 2: Flexible Backplane Implementation
Flexible
Storage
Backplane
New Universal Bays:
Enterprise PCIe or SAS or SATA
new
PCIe x4
SAS
SATA
New
PCIe
Controller,
ePCIe
Root port
SAS
SATA
Expanders
Existing Bays: SAS or SATA
SAS
SATA
1.4
SAS
SAS
SAS
Controller
SAS
SAS
SAS
SAS
SATA
Scope
This is a form factor specification that focuses on extending the existing connector for PCIe use. The new
connector is a backward compatible extension of the existing SAS connector (SFF-8482, 2006). The
8
Enterprise SSD Form Factor 1.0a
overall mechanical form factor is compliant with the 2.5” form factor (SFF-8223, 2006) or 3.5” form factor
(SFF-8301, 2010).
This specification defines the following:






1.5
Pin list and pin out of the new connector.
Mechanical definition of the new connector, including latching, keying, and retention.
Limited electrical specification (largely reference PCIe CEM and SAS Specifications).
Hardware hooks for Hot Swap
Signal definitions for Dual Port
Definitions of a basic product data accessible from SM-Bus
Outside of Scope
This specification is only normative for connector and related definitions (just listed)
The actual usage is not defined. While we envisioned having an SSD using NVM Express interface
(NVM Express, 2011) or SOP (SCSI over PCIe) (T10, SOP, Draft 2012), these are not required and other
PCIe device interface models would work.
The specification does give possible usage (aka. implementation notes) for Hot Swap, Dual Port, and SMbus but the details are system implementation specific. These are just meant to illustrate a possible
usage.
Specifically this specification is informative (not normative) in the following areas:





The drive outline is defined by EIA/ECA-720 (SFF-8223, 2006) for 2.5” drives or by EIA-740
(SFF-8301, 2010) for 3.5” drives. The drive carrier and storage enclosure are implementation
specific.
Mechanical drawings normative document is SFF-8639 (SFF-8639, 2012). Section 3 is
informative, for ease of reference.
SAS signal definitions and specifications – normative are the SAS Specifications (T10, Various).
Note: SAS-x4 signal definitions in this specification are a draft proposal to T10. This includes
SOP (SCSI over PCIe).
PCIe signal definitions and specifications – normative are the PCIe Specifications (PCI SIG,
various).
SATA/SATA Express signal definitions and specification – normative are the SATA Specifications
(SATA-IO, various).
Note: SATA Express signal definitions in this specification are a proposal to the SATA-IO Cabcon





SM Bus signal definitions and specifications – normative are the SM Bus specifications (SMBus,
2000)
PCIe device functionality and register details and the SM-bus registers are defined by the specific
device specifications. Likely referencing the PCIe Specification for standard PCIe device
discovery and setup.
Specific system implementation of presence pins (hot plug)
Specific system implementation of dual port functionality
References to other related connectors - specifically keying and overlaying of pins.
This is envisioned as a PCIe SSD specification and there is no standardization for additional connections
beyond the drive PCIe connector. There are both backplane and cable versions of the connector
receptacle.
9
Enterprise SSD Form Factor 1.0a
2 Signal List
The signal list is a combination of SAS/SATA and PCIe signals. Figure 3: Signal List Summary gives an
overview of the signal groups. Figure 4: Signal List Table gives the complete signal list, usage, and which
document is normative for the signal definition. Most of the signals used in this specification are defined
in other documents. Figure 5 gives the mapping of signal pins to connector pins.
2.1
Signal Lists
Figure 3: Signal List Summary (pin counts)
New
Enterprise
PCIe,
(E1E25.
S16-S28)
Existing
SAS/SATA
(S1-S14)
Usage
Signals
Contacts
x4 PCIe Gen3
4 lanes (Tx,Rx) (diff+gnd)
= 4*(4sig+2gnd) +1gnd(end)
(S16-S28 shared with lanes 2-3 of SAS x4)
25
(16 sig, 9 Gnd)
PCIe Sideband -
Enterprise Reset, RefClk (diff+gnd)
4
SM-bus(2), 3.3V-aux, Reserved(2)
5
4
PCIe optional
nd
1
Dual Port support
2 Reset, RefClk (diff+gnd), DualPortEn#
5
2 SATA/SATA
2
Express/SAS Ports
2 lanes (Tx,Rx) (diff+gnd)
= 2 ports * 7 pins
14
(8 sig 6 Gnd),
Power return
Gnd
3
12V (25W max)
3
5V
3
Power
Existing
Power
(P1-P15)
SATA/SAS Power Rail
2
2
Shared side band
SATA Express Sideband
Presence, Interface Detect , Activity
2
3
3
Client Reset, Reserved(Wake/OBFF#) ,
3
Reserved(ClkReq#/DevSLP)
Total
3
68
39 new,
29 existing,
2
(4 redefined )
The following are the notes on the signal list:
1. The high speed signals (PCIe lanes) are separate from SATA Express and Enterprise PCIe
SSD. This is driven by system requirements. There are separate PCIe Reset signals. See
Section 10.1 for details.
2. This specification and SATA Express replace the 3.3V signals and 1 ground with PCIe
sideband signals: Interface Detect, Client Reset, and new reserved signals,
Reserved(WAKE#/OBFF#), Reserved(CLKReq#/DevSLP).
3. Reserved(WAKE#/OBFF#) and Reserved(ClkReq#/DevSLP) are optional, and are for system
and device power management. The usage for power management of SSD devices is not yet
completely defined and are new proposals to the PCI Express standard (PCI SIG ECNs,
various).
4. SATA Express (client PCIe) proposal includes an optional RefClk. When the optional RefClk
is not present it will be dependent on PCI-SIG (PCI SIG ECNs, various) changes to support
independent spread spectrum clocks (with increased skip ordered set insertion). This is not
currently available but is anticipated in future revisions of the PCI-SIG.
10
Enterprise SSD Form Factor 1.0a
Figure 4: Signal List Table (defining specification)
Pin Group
Pin Name
PCIe High
Speed
PETp0, PETn0, PETp1, PETn1,
PETp2, PETn2, PETp3, PETn3
PERp0, PERn0, PERp1, PERn1,
PERp2, PERn2, PERp3, PERn3
PCIe Side
Band
PCIe
Optional
Side Band
Dual Port
PCIe Side
Band
SAS High
Speed
2nd Port
SAS High
speed
SAS x4
High
speed
SAS
support
Shared
Support
Defining
Specification
PCIe x4 Transmit
Enterprise PCIe
PCIe
PCIe x4 Receive
Enterprise PCIe
PCIe
RefClk0+, RefClk0-
PCIe RefClk (primary port A)
ePERst0#
Enterprise PCIe Reset (Port A)
SMClk, SMDat
SM Bus
3.3VAux
Power for SMbus accesses
RSVD(WAKE#/OBFF#)
RSVD(ClkReq #/DevSLP)
sPERst#
RefClk1+, RefClk1ePERst1#
DualPortEn#
S2T+, S2T-, S3T+, S3T-
Reserved for system/device
power management
SATA Express/SAS Reset
PCIe RefClk (dual port, port B)
Enterprise PCIe Reset (Port B)
Dual Port PCIe enable(2@x2)
SAS 0 Transmit
(SATA/SATA Express Transmit)
SAS 0 Receive
(SATA/SATA Express Receive)
SAS 1 Transmit
(SATA Express Transmit)
SAS 1 Receive
(SATA Express Receive)
Additional SAS X4 transmit
S2R+, S2R-, S3R+, S3R-
Additional SAS x4 receive
SAS Reset
Additional SAS Reset
SAS 2nd Activity
Additional SAS 2nd Activity
Activity
Drive Active
Presence; (Drive type encoded
on PRSNT# and IfDet#)
Interface Detect (Drive type
encoded on PRSNT# and IfDet#)
Only power for Enterprise PCIe
Power for SAS, SATA, SATAe
Reclaimed pins for SATA Express
sideband
S0T+ (A+), S0T- (A-)
S0R- (B-), S0R+ (B+)
S1T+, S1TS1R+, S1R-
PRSNT#
IfDet#
12V
5V
Power
Usage
Signal Description
3.3 V
GND
Notes: SATAe  SATA Express
Enterprise PCIe
Optional SATAe
Enterprise PCIe
Enterprise PCIe,
SAS x4
Enterprise PCIe,
SAS x4
ePCIe, SATAe
ePCIe, SATAe
SAS, SATAe only
Dual Port ePCIe
Dual Port ePCIe
Dual Port ePCIe
11
This Spec
SM Bus
This Spec
PCIe
PCIe
PCIe
PCIe
This Spec
This Spec
SAS, SATA/SATAe
SAS, SATA
SAS, SATA/SATAe
SAS, SATA
SAS, SATAe only
SAS, SATAe
SAS, SATAe only
SAS, SATAe
Overlapped with
PET1/PER1,
PET2/PER2
Overlapped with
SATAe sPERst#,
OBFF#
Shared
SAS x4
SAS x4
SAS x4
SAS x4
Shared
SAS, SATA/SATAe
SAS, SATA
This Spec,
SATAe
This Spec,
SATAe
This Spec
SAS, SATA
Not used
SAS, SATA
Shared
Shared
Shared
ePCIe  Enterprise PCIe
PCIe
Enterprise SSD Form Factor 1.0a
2.2
Connector pin out
Figure 5: Pin Out Drawing (Receptacle pin naming).
Drive
Usage
Signal Description
Name
Ground
GND
Mating Pin #
2nd
input SAS+SATA SAS/SATA/SATAe 0 Tx+
S0T+ (A+)
3rd
S2
input SAS+SATA SAS/SATA/SATAe 0 Tx -
S0T- (A-)
3rd
S3
Ground
GND
2nd
S4
output SAS+SATA SAS/SATA/SATAe 0 Rcv -
S0R- (B-)
3rd
S5
output SAS+SATA SAS/SATA/SATAe 0 Rcv +
S0R+ (B+)
3rd
S6
input
input
input
input
input
Bi-Dir
Dual Port
Dual Port
ePCIe opt
Dual Port
ePCIe
input
SATAe
input
SATAe
Ground
GND
ePCIe RefClk + (port B)
ePCIe RefClk – (port B)
3.3V for SM bus
ePCIe Reset (port B)
ePCIe Reset (port A)
Reserved (vendor)
RefClk1+
RefClk13.3Vaux
ePERst1#
ePERst0#
RSVD(Vendor)
3rd
3rd
3rd
3rd
3rd
3rd
E1
E2
E3
E4
E5
E6
Reserved(WAKE#/OBFF) RSVD(Wake#)
3rd
P1
3rd
P2
SATAe Client
sPCIeRst
input SATA+PCIe Reserved(ClkReq#/DevSLP) RSVD(DevSLP)
output
SATAe +
ePCIe
Interface Detect
(Was GND-precharge)
IfDet#
Ground
GND
all
all
input SAS+SATA
input SAS+SATA
Precharge
SATA, SATAe, SAS only
2nd
2nd
1st
Bi-Dir
Presence (Drive type)
PRSNT#
all
Activity(output)/Spinup
Activity
all
Hot Plug Ground
GND
input
all
input
all
input
all
All – 12V
Only power for ePCIe SSD
P4
2nd
P6
2nd
P7
3rd
P8
3rd
P9
2nd
3rd
1st
12 V
P10
P11
P12
2nd
Precharge
P3
P5
input SAS+SATA
all
S7
2nd
5V
Pin #
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
E17
E18
E19
E20
E21
E22
E23
E24
E25
S1
P13
3rd
P14
3rd
P15
ePCIe  Enterprise PCIe (separate from SATA/SAS)
SATAe  SATA Express
(Client PCIe- muxed on SATA/SAS signals)
SAS4  SAS x4
12
Mating
3rd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
2nd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
2nd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
2nd
3rd
3rd
3rd
Name
RefClk0+
RefClk0GND
PETp0
PETn0
GND
PERn0
PERp0
GND
RSVD
GND
S1T+
S1TGND
S1RS1R+
GND
RSVD
GND
PETp1/S2T+
PETn1/S2TGND
PERn1/S2RPERp1/S2R+
GND
PETp2/S3T+
PETn2/S3TGND
PERn2/S3RPERp2/S3R+
GND
PETp3
PETn3
GND
PERn3
PERp3
GND
SMClk
SMDat
DualPortEn#
Signal Description
Usage
ePCIe Primary RefClk + ePCIe+SATAe
ePCIe Primary RefClk - ePCIe+SATAe
Ground
ePCIe 0 Transmit +
ePCIe
ePCIe 0 Transmit ePCIe
Ground
ePCIe 0 Receive ePCIe
ePCIe 0 Receive +
ePCIe
Ground
Reserved
Ground
SAS/SATAe 1 Transmit + SAS+SATAe
SAS/SATAe 1 Transmit - SAS+SATAe
Ground
SAS/SATAe 1 Receive - SAS+SATAe
SAS/SATAe 1 Receive + SAS+SATAe
Ground
Reserved
Ground
ePCIe 1 /SAS 2 Transmit + ePCIe+SAS4
ePCIe 1 /SAS 2 Transmit - ePCIe+SAS4
Ground
ePCIe 1 /SAS 2 Receive - ePCIe+SAS4
ePCIe 1 /SAS 2 Receive + ePCIe+SAS4
Ground
ePCIe2 / SAS 3 Transmit + ePCIe+SAS4
ePCIe2 / SAS 3 Transmit - ePCIe+SAS4
Ground
ePCIe 2 / SAS 3 Receive - ePCIe+SAS4
ePCIe 2 / SAS 3 Receive + ePCIe+SAS4
Ground
ePCIe 3 Transmit +
ePCIe
ePCIe 3 Transmit ePCIe
Ground
ePCIe 3 Receive ePCIe
ePCIe 3 Receive +
ePCIe
Ground
SM-Bus Clock
PCIe opt
SM-Bus Data
PCIe opt
ePCIe 2x2 Select
Dual Port
Drive
input
input
input
input
output
output
input
input
output
output
input
input
output
output
input
input
output
output
input
input
output
output
Bi-DIr
Bi-Dir
input
Enterprise SSD Form Factor 1.0a
Notes on Pin out table







Relative to Standard SATA and SAS connector’s retention detents: new Pins E9-E12 & S21-S24
& E18-E21 (yellow shaded pin numbers) displaced required SAS connector retention detents. A
side latch is used for Enterprise PCIe cable retention described in Section 3.5.
"Drive" column shows signal direction relative to the plug connector (Enterprise PCIe SSD). Input
means sourced by the system. Output means sourced by the Enterprise PCIe SSD device and
an input to system.
"Name" and "Signal Description" columns are relative to the receptacle connector (backplane).
o The SAS specification labels the pins based on if it is a plug (drive) or receptacle
(backplane). The SAS receptacle connector pin-out (shown) uses naming relative to the
host, while the SAS plug connector pin-out (not-shown) is relative to the Enterprise PCIe
SSD.
o This document uses PCIe convention. PCIe pin-out is always relative to the host. The
following is from the PCIe Specification (PCI SIG CEM, 2007).
 “[PCIe Transmit (i)+] PETp<i> and [PCIe Transmit (i)-] PETn<i> pins (the
transmitter differential pair of the connector) shall be connected to the PCI
Express transmitter differential pair on the system board, and to the PCI Express
receiver differential pair on the add-in card.
 These pins are inputs on an Enterprise PCIe SSD.
 “[PCIe Receive (i)+] PERp<i> and [PCIe Receive (i)-] PEPn<i> pins (the receiver
differential pair of the connector) shall be connected to the PCI Express receiver
differential pair on the system board, and to the PCI Express transmitter
differential pair on the add-in card.
 These pins are outputs of an Enterprise PCIe SSD.
Pins P1-P3 SATA Express sideband signals are redefined from SATA & SAS specifications which
defined these pins as 3.3V. The 3.3V rail is not widely used on existing products and SATA
Express is using these for sideband signals. Drive pins P1-P3 should be tolerant of 3.3V applied
from the system.
Pin P4 is now Interface-Detect (IfDet#) and is redefined from SATA & SAS specifications which
st
defined this pin as a ground. It remains 1 mate.
Pin P3-Reserved(ClkReq#/DevSLP) is listed as Reserved since the usage is not yet specified for
Enterprise PCIe SSDs. The ClkReq# mode is used in some PCIe client devices (SATA-IO, Draft
2011). The DevSLP mode is defined for legacy SATA devices (SATA-IO, 2011).
Pin P1-Reserved(WAKE#/OBFF#) is listed as Reserved since the usage for Enterprise PCIe SSD
is not completely understood.
SATA Express pin placement is only a proposal on how to align this specification’s Enterprise
PCIe pin-out with proposals for pins in SATA Express. The SATA Express signals are not yet
standardized, and this document is not the normative document on pin out or pin definition for
SATA Express.
SAS-x4 pin placement is a proposal on how to align this specification’s Enterprise PCIe pin-out
with proposals for pins to support SAS-x4
13
Enterprise SSD Form Factor 1.0a
2.3
PRSNT# - Presence Detect and IfDet# - Interface Detect Signal Definition
The Presence (PRSNT#) is similar to Presence on the existing SFF-8482 connector. There is a
redefinition of the IfDet# (pin P4) to encode drive type. The usage of the combined signals is to detect a
drive is present and the drive type. Figure 6 shows how the drive type can be decoded from PRSNT# and
IfDet# pins. .
Figure 6: Drive type - Pin decoding
P10
PRSNT#
P4
IfDet#
E25
DualPortEn#
Comment
(was GND)
Driveoutput
Driveoutput
Drive= Input
SATA/SAS
Gnd (drv)
Gnd (drv)
Open(NC)
Existing Drive
(P4 is GND, E25 is NC)
SATA Express
(Client PCIe)
Gnd (drv)
Open (drv)
Open(NC)
PCIe on SATA/SAS lanes (S1-S14)
sPERst# is used, no RefClk used
(P4 is NC, E25 is NC)
Enterprise PCIe
(SFF-8639)
Open (drv)
Gnd (drv)
High (by
system)
PCIe are on new Enterprise lanes (E7-E15,
S16-S28, E17-E22)
RefClk0 and ePERst0# are used
Dual Port
Enterprise PCIe
(SFF-8639)
Open (drv)
Gnd (drv)
Low (by
system)
PCIe are on new Enterprise lanes (
PortA = E7- E15, S16-S22
PortB = S22-S28, E17-E22)
RefClk0, ePERst0#, and
RefClk1, ePERst1# are used
No drive
present
Open (drv)
Open (drv)
-
1
All open
1. SATA Express may define IfDet# as a pull up & resistance. The SATA Express documentation is
normative.
Either P10 or P4 being low indicates a drive is present. Further decoding is when P4 is open, then the
PCIe lanes use the SATA pins (S1-S14) as defined for SATA Express.
In-band signal discovery is used to determine SATA vs. SAS. In-band signal discovery is used for width
(x1, x2, x4) determination for SAS and PCIe. This is consistent with the existing SAS and PCIe standards.
2.4
DualPortEn# - PCIe Dual Port Enable
The Enterprise PCIe SSD can be configured to train as either a single x4 controller or dual x2. The
mechanism for enabling dual port operation is DualPortEn# (pin E25). DualPortEn# is pulled high internal
to the Enterprise PCIe SSD. If DualPortEn# is left open then the PCIe is configured as Single x4 port. If
DualPortEn is pulled low by the system (driven low or grounded by backplane), then the Enterprise PCIe
SSD has dual Ports enabled. DualPortEn# is part of the drive type determination shown in Figure 6.
DualPortEn# is a static signal. DualPortEn# must be stable 1uS before either ePERst[1:0]# are deasserted, and DualPortEn# can only change if both ePERst[1:0]# are asserted. The Enterprise PCIe SSD
may sample this signal at any time, and operation is undefined if DualPortEn# changes state during
operation. In practice is sampled during Enterprise PCIe SSD local reset sequence to configure the ports.
14
Enterprise SSD Form Factor 1.0a
The electrical signal characteristics of DualPortEn# follows the sideband interface signals of PCIe as
stated in PCIe CEM Specification 2.6 Auxiliary Signal Parametric Specifications (PCI SIG CEM,
2007).
Section 5.1 on page 33 gives more details on Dual Port operation.
2.5
Reserved(WAKE#/OBFF#), Reserved(ClkReq#/DevSLP)
The Reserved(Wake#/OBFF#), Reserved(ClkReq#/DevSLP), signals are all optional and are used in
device power management. These signals are defined by the PCIe Specification (PCI SIG ECNs,
various). At this time the pin definition and usage in Enterprise PCIe SSD is not completely defined, so
the pins are listed as reserved.
2.6
ePERst[1:0]# - PCIe Reset
The Enterprise PCIe Reset (ePERst[1:0]#) are logically the same as defined in the PCIe Specification
(PCI SIG CEM, 2007) but for Enterprise PCIe SSD there are additional input current requirements. This
allows for a drive to have pull up or pull down circuitry to support hot removal. This is defined in Section
7.3. There are two resets to allow for dual port operation, as defined in Section 5.
The Enterprise PCIe Reset (ePERst0#) is required to be supplied by the system for the Enterprise PCIe
SSD.
If DualPort# is asserted, then Port B Enterprise PCIe Reset (ePERst1#) is required to be supplied by the
system for the Port B of the Enterprise PCIe SSD.
2.7
RefClk[1:0][+/-] – Enterprise PCIe Clocks
The Enterprise PCIe Reference Clock (RefClk0[+/-]) should be supplied by the system for all Enterprise
PCIe SSDs.
If DualPort# is asserted, then Port B Enterprise PCIe Reference Clock (RefClk1[+/-]) should be supplied
by the system for all Port B (second port) of the Enterprise PCIe SSDs.
Implementation Note: RefClk is required for systems that use Spread Spectrum Clocking (SSC) to track
the changes in the reference clock. In a typical server system it is expected that Enterprise PCIe SSD will
need to use RefClk# for correct operation. This is the same as PCIe slots. RefClk does not need to be
supplied if both the platform and drive support SRIS - Separate RefClk with Independent SSC (PCI SIG
ECNs, various) or SRNS - Separate RefClk with No SSC (independent clocking).
Implementation Note: RefClk is required for Enterprise PCIe SSD but note that SATA-Express is
pursuing a PCI SIG specification change in future root ports that will enable no RefClk for SATA-Express.
2.8
Activity - Activity indication signal
The Activity signal asserts with drive activity. The blink patterns the same as for existing SAS drives, and
may have vendor defined blink patterns. The system use of the Activity signal is optional.
Implementation Note: An overview is the Activity signal is asserted when drive is active, but blinks off
"occasionally" during periods of continuous activity to distinguish it from other LED states. The Activity
signal is called “Ready” in the SAS documentation and the definition is in the SAS Protocol Layer - 2
(SPL-2) Specification (T10, SPL 2, 2011) in Section 9.4.1 SAS Ready signal behavior.
15
Enterprise SSD Form Factor 1.0a
3 Connector Mechanical
Note: this section with the connector mechanical drawing is informative. The normative specification is
SFF-8639(SFF-8639, 2012).
Figure 7 gives an overview of the mechanical layout of the connector. The new signals are shown in red.
Figure 8 gives an isometric view of representative examples of the connectors from multiple angles.
Figure 7: Connector Mechanical Overview
Primary Side (closest to drive edge)
PCI Sideband SAS/SATA/SATA Express
st
E6-E1
1 Port
(6 Pins)
S7-S1 (7 Pins)
Power, SATA Express sideband
P15-P1 (15 Pins)
PCIe Lanes 3-1, Sideband
E25-17, S28-S15
(23 Pins)
SAS/SATA Express
nd
2 Port
S14-S8 (7 Pins)
rd
PCIe Lane 0, RefClk
E16-E7
(10 Pins)
th
SAS x4 - 3 -4 Port
S28-S16 (13 Pins)
Secondary Side
Figure 8: Connector Examples
Right Angle Plug
Right Angle Plug - rotated
Vertical Receptacle
Vertical Receptacle - rotated
16
Enterprise SSD Form Factor 1.0a
3.1
Connector Mechanical Drawing notes
The mechanical drawing of the connector plug (drive side) are shown in Figure 9 though Figure 17. The
mechanical drawings of the connector receptacle are shown in Figure 18 and Figure 19.
3.2
Connector Plug Mechanical Drawings
Figure 9: Connector Plug Mechanical Drawing – Top View
Figure 10: Connector Plug Mechanical Drawing – Drive Insertion View
17
Enterprise SSD Form Factor 1.0a
Figure 11: Connector Plug Mechanical Drawing – Bottom View (outside of enclosure)
Figure 12: Connector Plug Mechanical Drawing – End View (showing latch slot)
18
Enterprise SSD Form Factor 1.0a
3.3
Connector Plug Mechanical Drawings - Details
Figure 13: Connector Plug Mechanical Drawing – Detail A (key)
Figure 14: Connector Plug Mechanical Drawing – Detail C (key pins)
19
Enterprise SSD Form Factor 1.0a
Figure 15: Connector Plug Mechanical Drawing – Detail B (Tongue)
Figure 16: Connector Plug Mechanical Drawing – Section D-D (Tongue cross section)
20
Enterprise SSD Form Factor 1.0a
Figure 17: Connector Plug Mechanical Drawing – Drive Keep-out Area
3.4
Connector Receptacle Mechanical Drawings
Figure 18: Connector Receptacle Mechanical Drawing – Drive insertion view
21
Enterprise SSD Form Factor 1.0a
Figure 19: Connector Receptacle Mechanical Drawing – Section E-E (Receptacle)
3.5
Cable Retention Mechanical Drawings
The primary server and storage Enterprise PCIe SSD connection is a backplane with retention provided
by the drive carrier and storage enclosure. This is typically a universal driver carrier with insertion guides
and insertion/ejection lever and any required keying. The definition of the drive carrier is outside the
scope of this specification. The backplane receptacle connector is intended to be universal accepting all
the standard drive keys, relying on more mechanically robust storage enclosure keying.
A cable receptacle is defined for applications needing a cabled interface to the drive. The Enterprise PCIe
SSD cable (receptacle) interface incorporates an active latching retention mechanism to prevent
accidental disconnecting of the interface. The cable retention is a snapping latch when mated and a
press-to-release finger actuated button on the sides of the housing. This is different from existing SATA
and SAS connectors which use a friction detent on the secondary side of the tongue. An overview of the
Enterprise PCIe SSD cable retention is shown in Figure 20.
The Enterprise PCIe SSD cable (receptacle) has an extra keying feature to allow the Enterprise Cable to
be blocked from mating with SATA, SATA Express, and SAS drives. The “L” shaped key shall be
implemented on the Enterprise PCIe SSD cable receptacle. The “L” shaped key should not be
implemented on the Enterprise PCIe SSD backplane receptacle. A keying compatibility matrix is shown in
Section 10.3.
Figure 21 shows the mechanical drawing of the cable retention features that mate with the plug feature
shown in Figure 12. The latch slot shall be implemented on Enterprise PCIe SSDs plugs. (The drive
latch slot should not be implemented in SATA, SATA Express, and SAS drive plugs.) The latch shall be
implemented on Enterprise PCIe SSD cables. The size cable housing and location of finger release are
not specified, and these drawing are just informative. The clearance for a representative cable housing is
shown in Figure 22. A representative cable assembly with flat ribbon cables is shown in Figure 23.
Implementation note: An existing SAS cable would accept an Enterprise PCIe SSD drive but would not
function (no signal connections) and would have not engaged the SAS cable detent retention mechanism.
22
Enterprise SSD Form Factor 1.0a
Figure 20: Cable Retention: Latch and Key Overview
23
Enterprise SSD Form Factor 1.0a
Figure 21: Cable Retention Mechanical Drawing – Representative Cable Housing
24
Enterprise SSD Form Factor 1.0a
Figure 22: Cable Release Clearance - Representative Cable Housing
25
Enterprise SSD Form Factor 1.0a
Figure 23: Representative Cable Housing with flat ribbon cables
26
Enterprise SSD Form Factor 1.0a
4 Hot Plug and Removal
Enterprise PCIe SSDs shall support hot plug and removal, both with and without prior system notification
(surprise removal).
The fact that this is a physical hard drive form factor suggests that some characteristics of a hard drive
usage model will be supported. In today’s servers hard drives are hot pluggable with some limitations.
The Enterprise SSD drive shall be hot pluggable for both hot insertion and hot removal with and without
prior system notification or preparation. Without prior system notification is typically referred to as
“surprise insertion” and “surprise removal”.
Whether the user provides the system with notification of the hot plug event or not, many aspects of the
system are involved in processing such an event. Elements of the overall system that are impacted are
dependent on platform architecture and design but will typically include components of the PCIe
infrastructure such as switches, platform firmware (BIOS), the Operating System’s PCIe bus driver stack
and its IO stack. However, typically, a user would announce a hot plug event through one of the available
system management interfaces.
The goal of this specification is not to define an overall systems architecture and design to support hot
plug for the Enterprise PCIe SSDs but to define those elements of the hardware infrastructure that can be
utilized to support such a solution.
The objectives of the hot plug design are:



To provide a user experience similar to existing disk drive hot plug behavior.
Support all forms of hot insertion/removal
o OS aware insertion/removal
o Surprise insertion/removal
 Insertion
 Insertion into a slot that has power and clocks on
 Removal
 Removal from a slot that has power and clocks on
 Removal with TLPs in flight and outstanding host non-posted requests
o SAS based hot plug signaling or PCIe native hot-plug
No special controller requirements beyond those already defined in the PCIe base and in the
PCIe Card Electromechanical specs
o Allows standard PCIe controllers to be used in Enterprise PCIe SSD without modification
The issues to be addressed are:
1. Limiting of inrush current.
2. Detection of Enterprise PCIe SSD addition and removal and Determination of Drive Type – PCIe
vs. SAS
3. Drive management – reset
4. SW implications
System support for Enterprise PCIe SSD hot plug and removal as well as the level of support (i.e., OS
aware insertion/removal vs. OS and surprise insertion/removal) is implementation specific and outside the
scope of this specification.
Implementation Note: Surprise Hot Removal is a must have requirement from system vendors for PCIe
SSD devices. More specifically, it is expected that system vendors will require Enterprise PCIe SSD to
retain all “committed data” following a surprise hot removal. This implies that the Enterprise PCIe SSD
locally detect hot removal and store/destage any cache data. For a typical implementation this means the
following is implemented


Having power sustaining capability, such as a battery or super cap.
Detecting removal (by loss of 12V input or link loss)
27
Enterprise SSD Form Factor 1.0a


Copying all “committed data” from volatile storage (DRAM based write back cache) to non-volatile
storage. The details of this operation are complex, and implementation specific. The definition of
“committed data” is specific to the higher level interface but typically means acknowledged write
data. This “committed data” includes all indirection pointers to the data.
This copying of data has to be recovered upon PCIe SSD power on or hot addition. It is common
for data or indirection tables to be written in to a staging location to simplify power down. This has
to be reconstructed on power on/hot add to recover the full committed PCIe SSD state.
From a practical perspective for the Enterprise PCIe SSD, surprise hot removal is not that different from
surprise power fail. In system power fail 12V likely has a longer power down ramp, but that is not
guaranteed.
4.1
Limit current inrush
The Enterprise PCIe SSD shall limit the current inrush by leveraging the pre-charge approach from
SAS/SATA and combining this with the slot power limit approach from PCIe. The Enterprise PCIe SSD
shall:
a. Bus together all power and ground pins.
b. Limit the exposed capacitive load as specified in Section 7.4.
c. Adhere to the mechanical pin length as shown in Figure 28
 1 ground pin mate first (pin P12)
 12V precharge pin mates second (pin P13). In addition all the signal ground returns are
second mate.
 Remaining 12V pins mate third (Pin P14 and P15)
d. Initialize and enforce the Slot Power Limit PCIe configuration register to 10W value (Section 7.4).
This eliminates the need for the system power supply to handle worse case power at start up.
Figure 24: Hot Plug Current Inrush Limiting
Implementation Note: Limiting the inrush and hot plug support require merging information from a
number of sources. SFF-8639 (SFF-8639, 2012) has the mechanical specifications for blind mate
tolerance and the 0.5mm difference in mating pin length. The SATA Specification (SATA-IO, various)
st
gives a typical existing system insertion rates of 3ms delay from the 1 precharge 12V power to
28
Enterprise SSD Form Factor 1.0a
remaining power pins contacting. Given these parameters and the 12Vcap specification in Section 7.4,
the backplane resistance (RL in Figure 24) can be determined.
4.2
Detecting Enterprise PCIe SSD Insertion/Removal
There are multiple methods to detect PCIe SSD insertion or removal.


Use the drive type pins (PRSNT# pin P10, and IfDet#, pin P4). Note drive type can be
determined as described in Section 2.3.
Use of In-Band signaling. The PCIe or SAS links may be enabled to train periodically,
succeeding when device is plugged in. The PCIe or SAS links are lost when device is removed.
How system software is signaled is beyond the scope of this specification.
Implementation Note: There are three broad classes of usage of Presence (PRSNT#) and SATA Detect
(IfDet#) during hot insertion or removal.
1. A common implementation is expected to be that PRSNT# and IfDet# are routed to the existing
storage enclosure microcontroller and the microcontroller sends specific drive insertion or
removal information to system software using the management stack. This is a common SAS
implementation extended to two pins for 3 type encodings.
2. Alternatively the PRSNT# & IfDet# signals are simply turned into a general storage attention
interrupt, enabling the system software to probe the system for changes. This can be augmented
by examining if any PCIe link has changed status, or used as a trigger to enable Enterprise PCIe
SSD to test for link training.
3. Optionally an existing storage enclosure microcontroller can poll and read the SM-bus to read
vital product data (VPD) to learn specific information about the inserted device.
4. It is acceptable for the PRSNT# and IfDet# signals to be ignored completely by system hardware.
Enterprise PCIe SSD insertion detection can be done in-band by detecting the training of the
PCIe link. This may be complicated by PCIe links being disabled (powered down), so periodic rearming may be required to probe for newly added Enterprise PCIe SSDs. In this case Enterprise
PCIe SSD removal is detected by loss of PCIe link or PCIe link errors. From a timing perspective
st
the PCIe link error/loss is the common 1 detection of surprise removal since it is tightly coupled
with ongoing operation.
4.3
PCIe Hardware and Reset System Requirements
Enterprise PCIe SSD Reset/power on and PCIe Hot Add follows the PCIe specification (PCI SIG CEM,
2007). Enterprise PCIe SSDs must generate their own internal power-on reset by detecting the power
ramp on 12V.
In all cases the Root Complex and system software shall allow at least 1.0 second after a Conventional
Reset of an Enterprise PCIe SSD, before determining that an Enterprise PCIe SSD which fails to return a
Successful Completion status for a valid Configuration Request, is an unresponsive or failed Enterprise
PCIe SSD. This 1.0 second is true for both PCIe and SMbus operations. This period is independent of
how quickly Link training completes.
PCIe Reset Card Requirements
●
●
Normal System Operation (not Hot Insertion/Removal)
o An Enterprise PCIe SSD shall adhere to PCIe system reset and card reset requirements
(Figure 25 and Figure 26)
Hot Insertion
o If reset asserted then an Enterprise PCIe SSD must adhere to PCIe system reset and
slot reset requirements.
 This also means that the system & root complex must adhere to these
requirements
o If reset negated
 Power and clock shall be stable 10ms after assertion of IfDet# (Enterprise PCIe
SSD’s Presence Detect)
 PRSNT# and IfDet# is in the last (3rd) group of pins to mate
29
Enterprise SSD Form Factor 1.0a



●
This consumes 10ms of the 100ms power stable time in Figure 25 and
Figure 26.
Enterprise PCIe SSD shall generate its own internal reset
Logically PCIe reset is considered to have occurred 100ms after PRSNT# pin
mating
 An Enterprise PCIe SSD must adhere to PCIe system reset
requirements from this point on
 This simply shifts timing parameters on Figure 26 by 100ms
o This shift must also be comprehended by the platform if hot
insertion occurs during a normal PCIe system reset sequence.
Hot Removal
o On a Hot Removal the Enterprise PCIe SSD shall perform any necessary clean-up and
retain on the PCIe SSD any previously acknowledged write operations
Figure 25: System Reset Timing
30
Enterprise SSD Form Factor 1.0a
Figure 26: Reset Timing Details (PCI SIG CEM, 2007)
4.4
Software Implications of Hot Swap (Informative)
The software implementation is outside the scope of the specification; however this section provides
some guidelines for OS and BIOS/Firmware implementers. Please refer to appropriate system
BIOS/Firmware and system software (OS, VMM) for normative documentation.
The typical issues SW must handle on Hot Add include:
●
●
●
●
Discover the Enterprise PCIe SSD location
o Discovery may be assisted by management software or PRSNT# pin.
o Software may have to enable a PCIe link (kick link out of power down mode)
PCIe plug and play
o PCIe configuration: map the new Enterprise PCIe SSD into the PCIe space, and do any
space allocation and resource rebalancing.
o Load the appropriate software drivers.
Map the Enterprise PCIe SSD into the name space of the file system. This may include
rebuilding any RAID arrays damaged by an earlier failure, or mapping to new on-the-fly RAID or
tiering configuration.
Finally start using the PCIe SSD
The types of issues SW must handle on Hot Remove include:
●
●
Map the Enterprise PCIe SSD out of any RAID, tiering configuration – prepare stack for
Enterprise PCIe SSD removal.
Stop using the Enterprise PCIe SSD, send commands to “prepare for removal”
o Typically this causes any write cache to flush, and any mapping table to be written back
31
Enterprise SSD Form Factor 1.0a
o
●
●
If Enterprise PCIe SSD is not notified before removal, then it is surprise removal, see
next section.
Optionally use management system to identify the Enterprise PCIe SSD to remove. For example
blink a red light for failure indication.
User safely removes the Enterprise PCIe SSD.
If the removal is “surprise” meaning that the Enterprise PCIe SSD is active as it is being removed then the
system software implications grow. These include, but are not limited to, the handling of errors during
surprise removal event.
The software implications vary with the PCIe root port implementation and OS/SW versions.
software implications are beyond the scope of this specification.
The
Implementation Note: A complication of Hot Removal is discovering and testing all the boundary cases
of the hardware/software interaction. In general a clean HW/SW interface and a clean software
implementation are warranted – for example not a legacy interrupt model. The basic mechanism for an
error detected by an instruction (ld/st) failure is to fault then handle the fault with by aborting the transfer.
It is expected that any data in flight at the time of removal is lost or corrupted. Hardware is only expected
to retain “acknowledged and committed data”.
Implementation Note: It is expected that older versions of the operating system and PCIe root port will
not be able to support surprise Hot Removal. With older OS/HW the errors during surprise removal might
generate a fatal error.
New versions of the PCIe root port will be design to signal to the system software (BIOS and OS) to
handle the hot removal event. The details are beyond the scope of this specification. The documents are
not yet released. This detail is expected in documents such as the System BIOS Writers Guide for the
root port component.
Implementation Note: Windows client OS is surprise hot remove capable because it was designed to
support ExpressCard form factor. The Slot Capabilities Register contains a bit called Hot Plug Surprise
which is a form factor specific bit. Express Card was expected to set this bit to indicate to Windows that
card could be removed without notification and software stack should handle this without failure or data
loss. For example, any writes to media behind such a card should never be cached by OS.
Since the Server OS shares a common code base with the Client OS at the kernel level, the basic
capability exists in Windows Server but is not validated.
An outline of how Enterprise PCIe SSD Hot Swap will work:
-
-
The OS gets signaled that an Enterprise PCIe SSD is inserted. (Using PCIe Hot Plug
mechanism, a custom OEM leveraged mechanism, or detecting a change in PCIe Link Status.)
OS enables read caching but not software write caching since the Enterprise PCIe SSD is
surprise remove capable (if this impacts performance, then IT has to ensure they go through
software UI to prep for ejection first).
When the Enterprise PCIe SSD is removed cleanly, the error handling will abort any active
transfers, then the presence detect toggle will indicate the hot remove event to OS
OS will unload the corresponding driver stack and complete all pending IO request packets.
32
Enterprise SSD Form Factor 1.0a
5 Dual Port Operation
The Enterprise PCIe SSD may optionally support Dual port operation. The expectation is that servers
and other single controller systems will use Enterprise PCIe SSDs in a single x4 configuration. High
Reliability Storage Controllers with redundant controllers will use two x2 links. In dual port mode the data
on the Enterprise PCIe SSD is accessible from either controller allowing for failure of a controller. In dual
port modes the Enterprise PCIe SSD acts independently as a PCIe device on each link. This is shown
in Figure 27: Single Port and Dual Port example.
Implementation Note: Dual port operation is optional but is expected to be a required feature by storage
vendors
Figure 27: Single Port and Dual Port example
Typical Server configuration
PCIe x4
(e.g. CPU x4
PCIe port)
Controller
Cmd Q
SSD Form Factor
Device
(Enterprise PCIe SSD)
Typical Storage configuration
PCIe x2
PCIe x2
Connector
A
Connector
PCIe upstream
Controller
SSD Form Factor
Device
Data
DataQQ
Data Q
Data Q
Cmd Q
Data
DataQQ
Data Q
Data Q
(Enterprise PCIe SSD)
Cmd Q
B
Data
DataQQ
Data Q
Data Q
.
The two PCIe links must operate independently. It is expected that both ports are fully PCIe compliant
devices and as such each port presents a fully a PCIe compliant endpoint.
It is possible that the PCIe device is a multi-root PCIe switch, but that is not expected to be the common
solution. In this solution resets and failures (such as errors and clock failures) on one port must not affect
operation on the other port.
Implementation Note: In the most common dual port usage the Enterprise PCIe SSD appears as a
totally independent Enterprise PCIe SSD on each bus sharing media. In Figure 27 both Controller A and
Controller B see standard PCIe devices. There is not expected to be a PCIe-probe SW discoverable
connection to the other port. There are two completely independent interfaces – such as two independent
sets of PCIe configuration space, memory mapped control registers and queues. A higher level
mechanism (such as reporting the same GUID on both links, or inherent knowledge of the topology) allow
high level storage software to detect that the two Enterprise PCIe SSD controllers are sharing a common
pool of storage and the higher level software coordinates the allocation of resources.
33
Enterprise SSD Form Factor 1.0a
Implementation Note: All Enterprise PCIe Devices have a single supply and single ground return plane.
For signal integrity there MUST be a single ground plane. Any redundant supply is handled outside the
Enterprise PCIe SSD.
This specification places no access restriction or interlocks on the usage of the two ports. Specifically
writing independently to the same storage block from both ports the ordering is not guaranteed. Higher
level software or system architecture is assumed to prevent any unsafe overlapping commands.
5.1
Dual Port Mode (implications of DualPortEn#)
The Enterprise PCIe SSD may be configured to train as either a single x4 port (port A) or dual x2 ports
(i.e., ports A and B). When DualPortEn# (pin E25) is asserted (typically grounded by storage backplane),
then the Enterprise PCIe SSD shall be configured for dual port operation. DualPortEn# is left
unconnected or undriven by the system for single port operation. The Enterprise PCIe SSD shall pull
DualPortEn# high (deasserted) if left unconnected by the system.
When configured for single port operation, the following rules apply:
●
●
●
●
●
Enterprise PCIe SSD shall not train as two independent links.
Enterprise PCIe SSD may train as a single x4, x2 or x1 link. Support for x2 is optional for both
the system and the PCIe SSD.
Enterprise PCIe SSD shall use ePERst0# to control the PCIe interface as defined by PCIe
specifications (PCI SIG CEM, 2007).
Enterprise PCIe SSD may use RefClk0 (if operating in common clock mode)
Enterprise PCIe SSD shall ignore dual port signals, RefClk1, ePERst1#.
When configured for dual port operation, the following rules apply:
●
●
●
●
●
●
●
Port A shall use PCIe lanes 0 and 1. Port B shall use PCIe lanes 2 and 3.
Enterprise PCIe SSD shall not train as a single x4 link.
Enterprise PCIe SSD shall train as a dual independent x2 if both upstream controllers are active
and the Enterprise PCIe SSD supports dual port.
Either port may train only as x2 or x1.
Enterprise PCIe SSD may train one port, both ports, or neither port.
Each PCIe port shall operate completely independently
o ePERst0# assertion/negation or loss of RefClk0 or errors affecting PCIe port A shall not
affect the operation on the PCIe Port B.
o ePERst1# assertion/negation or loss of RefCLk1 or errors affecting PCIe port B shall not
affect the operation on the PCIe Port A.
When an Enterprise PCIe SSD is not capable of dual port operation but is configured for dual port
operation, the following rules apply:
o Enterprise PCIe SSD should train on either port A or Port B in x2 or x1. This is to allow
just a single upstream controller active. This requires the appropriate PCIe Clock and
PCIe Reset to be used. Specifically if Port A is trained then RefClk0 and ePERst0# are
used, and if Port B is trained then RefClk1 and ePERst1# are used. For a single port
PCIe SSD support for Port B is optional, and support for Port A is required.
o Enterprise PCIe SSD shall not drive or terminate the signals on the port that is not
trained. Specifically: If Port A is trained, then Enterprise PCIe SSD shall not drive or
terminate Port B signals; or if only Port B is trained, then PCIe shall not drive or terminate
Port A signals.
Implementation Note: For a single port device that is presented with DualPortEn# asserted, it is
important to disable driving and terminating the unused pins because some upstream ports may detect
the electrical drive or termination as an electrical presence and try to train the port which would create
training errors. This capability can be implemented using standard PCIe IP block sitting on Port A, and
using the force width capability to disable the unused lanes, or by a separate HW disable derived from
DualPortEn# to disable lanes 2-3.
Implementation Note: There is a partial solution called Active/Passive mode. This is defined in Section
9.2.4.
34
Enterprise SSD Form Factor 1.0a
6 SM-Bus Operation
The Enterprise PCIe SSD should support SM-Bus operation. The SM-Bus protocol and signaling are
defined in the SM-Bus Specification (SMBus, 2000). SM-Bus operation is at 100khz or less.
SM-Bus is defined as independent of the PCIe links. There is no defined relationship between SM-Bus
accesses and accesses on the PCIe buses.
There are two level of SM-Bus access.
1. Single reads and writes to a PROM device holding VPD (Vital Product Data) used for Enterprise
PCIe SSD discovery and power allocation. Supported on 3.3Vaux power and during normal
operation. The register definitions are listed in Section 9.1 SM-Bus Vital Product Data (VPD).
Each Enterprise PCIe SSD’s VPD is expected to be independently addressed on a unique SMBus segment with VPD at a fixed address. SM-Bus ARP is not supported for VPD access. An
Enterprise PCIe SSD may require 3.3Vaux to be supplied to access this VPD data.
2. Extended management and access using MCTP-over-SMbus and this mode is only supported
during normal operation (e.g., when 12V is present). MTCP Commands are defined in Section
9.2
Implementation Note: While SM-Bus is optional for Enterprise PCIe SSD operation, it is expected to be
included in the Enterprise PCIe SSD purchase criteria by many system vendors.
Implementation note: This is specified to allow implementation with an I2C PROM connected to SM-Bus
and to 3.3Vaux. It is allowed to have the VPD with 3.3Vaux applied but required to apply 12V to access
optional extended management capabilities.
Implementation Note: The SM-Bus is not replicated for dual port operation. In dual controller
configuration, this is envisioned as going to a shared management agent, using the multi-master
characteristics of SM-Bus, or independent SM-Buses merged external to the Enterprise PCIe SSD.
6.1
Simple Accesses to Vital Product Data (VPD)
Enterprise PCIe SSD should support simple Reads and Write to Vital Product Data. This is defined in
Section 9.1 SM-Bus Vital Product Data (VPD) in summary it contains:



Basic inventory information such as type and size of Enterprise PCIe SSD, manufacturer, date,
revision, and GUID.
Power management data such as power level and power modes
Vendor specific data
Implementation note: This is likely implemented using a SM-Bus PROM connected to SM-Bus and to
3.3Vaux.
If a system vendor wants access to this data, then 3.3V shall be supplied to 3.3Vaux pins. If the system
vendor does not want access to this data via SM-bus, then 3.3Vaux may be optional.
6.2
Extended SM-Bus management
An Enterprise PCIe SSD may support full MCTP device access over SMbus (MCTP-over-SMbus). This
is only possible during normal operation (e.g. when 12V present).
The MCTP commands are beyond the scope of this specification.
Implementation Note:
The MCTP-over-SMbus is implementation dependent but is likely to support:



Access to VPD using MCTP semantics
Access to Enterprise PCIe SSD control registers
Access to underlying media (with protection mechanisms)
MCTP-over-SMbus is likely to be nearly symmetric with MCTP-over-PCIe.
35
Enterprise SSD Form Factor 1.0a
7 Electrical (pointer to other specifications)
The electrical characteristics of signals that are defined as part of other standards, particularly PCIe and
SAS, are referenced, rather than defined in this specification. This specification does define 2 signals,
and new absolute maximum values for the 12V power specification. The new signal DualPortEn#
complies with the PCIe auxiliary signal parametric specifications.
The signals at Pins P1-P3
(Reserved(ClkReq#/DevSLP), Reserved(Wake#/OBFF#), sPERst#) shall be 3.3V tolerant.
Figure 4: Signal List Table (defining specification) on page 11 defines which specification is normative for
each signal. This section gives electrical details on signals that are listed as “this spec” in Figure 4.
Note: For PCIe signals electrical compliance will be specified in a new PCI SIG document that is being
created by a PCI SIG electrical work group. A reference to that document will be included when it is
released.
7.1
Electrical Channel
The high speed electrical characteristics of the connector are the same as the SAS Specification (T10,
Various).
Implementation Note: There is ongoing work to get to higher frequencies and that will change the
channel definition, and possibly the connector requirements. That is outside the scope of this
specification.
Implementation Note: The electrical channel used in simulation is modeled after the typical server disks
connection. The typical channel is shown in Figure 28. Itemizing the channel from the upstream PCIe
transceiver toward the downstream Enterprise PCIe SSD port (letters correlate to Figure 28).
a. Upstream PCIe port transceiver and package
b. Short (<3”) lead in trace between upstream PCIe device and cable connector.
c. Internal cable – assuming a cable similar to SFF-8087 (SFF, various). The details are outside the
scope of this specification.
d. Short (<4”) lead in trace between cable connector and Enterprise PCIe SSD connector
e. Enterprise PCIe SSD connector – specified in this specification
f. Short (<2”) trace inside Enterprise PCIe SSD
g. Downstream PCIe port package and transceiver.
Figure 28: Typical SSD Form Factor Channel
Cable
Conn
Xcr
a
b
d
g
Connector
Conn
Motherboard
or Adaptor
card
8 pairs + sideband
e
c
Storage
Backplane
36
ASIC
f
SSD Form
Factor Device
Enterprise SSD Form Factor 1.0a
7.2
Presence and Interface Detect
Presence and Interface Detect are used to signal the SSD has been inserted. This is the same purpose
as SAS and SATA. The signal usage is given in Section 2.3 on page 14. In the drive the PRSNT# and
IfDet# are connected to ground or left not-connected to signal drive type with a system supplying a pull up
for signal detection.
7.3
ePERst[1:0]
The PCIe reset signal is logically identical as defined in the PCIe Specification (PCI SIG CEM, 2007).
There is a difference in the input current.
Parameter
Definition
Value
Comment
Iin
Reset pin Input Current
1mA
10uA in PCIe speciation
(PCI SIG CEM, 2007)
Implementation Note: This extended specification allows an Enterprise SSD drive to implement a circuitry,
such as a pull up, to control drive reset when a drive is being inserted or removed.
7.4
Power – 12V
An Enterprise PCIe SSD(s) shall get all its power from the 12V pins (P13-P15). However, 5V (P7-P9) and
3.3V (P1-P3) may be available for other drive types. For SM-bus support see 3.3Vaux below. Note: The
max current provided on 12V is greater than that specified in the SAS specification.
Figure 29: Power (12V) specifications
Parameter
Definition
Value
Pmax
Maximum power
25W (max)
Pinit-limit
Initial Slot Power Limit
10W (max)
12Vtol
Voltage Tolerance (at pin)
12Vamp
Max continuous current
12Vpeak-amp
Max peak current
Comment
Initial value until
updated by system
using a PCIe Slot
4
Power Limit message
See Note 5
1
2.45A (max)
2
Higher than PCI CEM
4.5A (max)
3
12Vcap
Max cap load
5uF (max)
12Vdrop
Voltage drop across connector
80mV
SM-Bus
delay
Delay from 12V being within spec
before SM-bus access to any
SM-bus slave address other than
VPD.
20ms (min)
Delay from PRSNT# connector
mating to an SM-bus access to
any SM-bus slave address other
than VPD.
20ms (min)
1.0s (max)
The Enterprise PCIe
SSD has up to 1.0s
before responding to
SM-bus transactions.
(Section 4.3)
1.0s (max)
1. Maximum continuous current is defined as the highest averaged current value over any one
second period.
2. Maximum current to limit connector damage and limit instantaneous power.
3. Maximum capacitance presented by the Enterprise PCIe SSD on the 12V power rail at the
backplane connector.
4. System Software can set a different lower limit using the PCIe Express Slot Capabilities register
defined in the PCIe Specifications (PCI SIG 3.0, 2010). This value can be set before an
37
Enterprise SSD Form Factor 1.0a
Enterprise PCIe SSD is installed, and the value will be sent to the device just after link training
and overrides this default. This is standard PCIe behavior.
5. No voltage tolerance is specified. Due diligence is need to confirm system and drive have
compatible specifications.
Implementation Note: To accommodate all drive types possible with a flexible backplane using SFF8639 connector, a 12V voltage tolerance of ±5% would conservatively support shipping SATA and SAS
drives. The SATA and SAS standards do not specify 12V voltage tolerance, but many existing drives
specify ±5% tolerance. The PCIe CEM (PCI SIG CEM, 2007) specifies ±9% on 12V in the standard PCIe
card edge form factor. System vendors commonly specify a voltage tolerance in their purchasing
specifications, commonly in the ±5-±8% range but not always symmetrical.
Note that Rev 1.0 of this specification specified a 12V voltage tolerance of ±15%, but this changed to
unspecified in Rev 1.0a. This is due to no single value being optimal for all flexible backplane
configurations.
7.5
Power 3.3Vaux
Enterprise PCIe SSDs may support 3.3V operation. SM-bus access is supported only when 3.3Vaux is
supplied.
The system may choose to not supply 3.3Vaux if limitation to SM-bus access is acceptable. The
Enterprise PCIe SSD shall operate even with no 3.3Vaux supplied. Enterprise PCIe SSD operation shall
not be dependent on 3.3Vaux except for SM-bus.
Implementation Note: Systems may connect 3.3VAux to either a standard 3.3V rail, or a special rail that
is powered even when system is in a standby state with main 12V rail disabled.
Implementation Note: A typical Enterprise PCIe SSD could connect a small PROM to SM-Bus and
power this device with 3.3Vaux. This VPD is only accessible if 3.3Vaux is applied by the system. SMBus could also be routed to the controller ASIC and these SM-bus operations would be dependent on
12V power rail.
Figure 30: Power 3.3VAux specifications
Parameter
Definition
3.3VAuxtol
Voltage Tolerance (at pin)
3.3VAuxamp
Max continuous current
1
Value
Comment
±15% (max)
Relaxed from PCIe CEM
20µA
(SM-Bus inactive)
Lower than PCI CEM
1mA
(SM-Bus active
or 12V applied)
2
3.3VAuxcap
Max cap load
SM-Bus delay
Delay from 3.3V being within spec
before SM-Bus access to VPD serial
EEPROM may be performed.
20ms (min)
Delay from PRSNT# & IfDet#
connector mating to when SM-bus
access to VPD serial EEPROM may
be performed.
20ms (min)
12V applied so system
not in S5-Soft Off (S5)
5µF (max)
1.0s (max)
The Enterprise PCIe SSD
has up to 1.0s before
responding to SM-bus
transactions. (Section
4.3)
1.0s (max)
1. Maximum continuous current is defined as the highest averaged current value over any one
second period.
2. Maximum capacitance presented by the PCIe SSD on the 12V power rail at the backplane
connector.
38
Enterprise SSD Form Factor 1.0a
8 References and Bibliography
8.1
References
PCI Express® Specifications are available from http://www.pcisig.com.
 PCI Express Base Specification, revision 3.0 (PCI SIG 3.0, 2010).
 PCI Express Base Specification, revision 2.1 (PCI SIG 2.1, 2009).
 PCI Express® Card Electromechanical Specification, Revision 2.0. April 11, 2007. Commonly
known as the “PCIe CEM” spec (PCI SIG CEM, 2007).
 PCI Express Engineering Change Notices, (PCI SIG ECNs, various)
Small Form Factor (SFF) specifications are available from ftp://ftp.seagate.com/sff
 SFF-8680 Specification for Unshielded Dual Port Serial Attachment Connector. Commonly
known as the “SAS drive connector” (SFF-8680, 2012). This is the new 12Gbps version of SFF8482 which has been transferred to the ECIA and is now officially known as EIA-966 (SFF-8482,
2006).
 SFF-8223 Specification for 2.5” Drive Form Factor with Serial Connector. Commonly known as
the “2.5” drive”. (SFF-8223, 2006)
 SFF-8301 Specification for 3.5” Drive Form Factor. Commonly known as the “3.5” drive” (SFF8301, 2010).
SSD HW/SW interface specification available from http://www.nvmexpress.org/ .
 NVM Express (formerly eNVMHCI). This is the HW/SW interface for a PCIe based controller
Non-Volatile (Flash, PCM) memory. Commonly known as “NVMe” (NVM Express, 2011),
SOP/PQI HW/SW interface specification available from http://www.t10.org/drafts/ .
 SCSI over PCIe (SOP) and PCIe Queuing Interface (PQI) . This is an SCSI derived HW/SW
interface for a PCIe based SSDs. Commonly known as “SOP/PQI” (T10, SOP, Draft 2012) (T10,
PQI, 2012),
8.2
References Under Development
The following are documents that are under development, but are not current publically available.
 STA SAS-3 WG – SCSI Trade Association’s Serial Attached SAS 3 generation Working Group.
Defining a 12Gbps version for SAS disk standard. Commonly known as the “SAS-3” (T10, SAS-3,
Draft 2012).
 SATA Express. Defining a next generation of the SATA standard that uses PCIe interface for high
performance drives. Also referred to in this specification as “Client PCIe” (SATA-IO, Draft 2011).
8.3
Formal Bibliography
NVM Express. (2011, July 12). NVM Express Revision 1.0b. Retrieved December 13, 2011, from NVM
Express: http://www.nvmexpress.org/
PCI SIG 2.1. (2009, March 4). PCIe® Base Specification, Revision 2.1. Retrieved from PCI SIG:
http://www.pcisig.com/specifications/pciexpress/
PCI SIG 3.0. (2010, November 10). PCIe® Base Specification Revision 3.0. Retrieved from PCI SIG:
http://www.pcisig.com/specifications/pciexpress/
PCI SIG CEM. (2007, April 11). PCI Express® Card Electromechanical Specification Revision 2.0.
Retrieved from PCI SIG: http://www.pcisig.com/specifications/pciexpress/
PCI SIG ECNs. (various). PCI Express Specifications & ECNs. Retrieved from PCI SIG:
http://www.pcisig.com/specifications/pciexpress/specifications/#ecn2
39
Enterprise SSD Form Factor 1.0a
PCI
SIG.
(various).
PCI
Express
Specifications.
http://www.pcisig.com/specifications/pciexpress
Retrieved
from
PCI-SIG:
SATA-IO. (2011, July). Serial ATA Revision 3.1 Specification. Retrieved from Serial ATA Internation
Organization (SATA-IO): https://www.sata-io.org/developers/purchase_spec.asp
SATA-IO. (Draft 2011, Not yet published). SATA Express. Retrieved from Serial ATA International
Organization: https://www.sata-io.org/technology/sataexpress.asp
SATA-IO. (various). SATA and SATA-Express. Retrieved from Serial ATA Internation Organization
(SATA-IO): http://www.sata-io.org/
SFF. (various). SFF Specifcations. Retrieved from Small Form Factor Web Site: http://ftp.seagate.com/sff
SFF-8223. (2006, May). 2.5” Drive Form Factor with Serial Connector. Retrieved from SFF site:
ftp://ftp.seagate.com/pub/sff/SFF-8223.PDF
SFF-8301. (2010, March 16). 2.5” Drive Form Factor with Serial Connector. Retrieved from SFF site:
ftp://ftp.seagate.com/sff/SFF-8301.PDF
SFF-8482. (2006, February 1). EIA-966, Serial Attachment 2X Unshielded Connector. Retrieved from
SFF site in lieu of EIA: ftp://ftp.seagate.com/pub/sff/SFF-8482.PDF
SFF-8630. (2012, June 15). Serial Attachment 12 Gb/s 4X Unshielded Connector, rev 1.1. Retrieved from
SFF: ftp://ftp.seagate.com/sff/SFF-8630.PDF
SFF-8639. (2012, June). Multifunction 12 Gbps 6X Unshielded Connector. Retrieved from SFF:
ftp://ftp.seagate.com/sff/SFF-8639.PDF
SFF-8680. (2012, July 11). Serial Attachment 12 Gb/s 2x Unshielded Connector, rev 1.6. Retrieved from
SFF: ftp://ftp.seagate.com/sff/SFF-8680.PDF
SMBus. (2000, August 3). System Management Bus (SMBus) Specification. Retrieved from SM Bus:
http://smbus.org/specs/smbus20.pdf
T10. (Various). INCITIS, Technical Committee T10 - SCSI Storage Interfaces. Retrieved from SCSI
Storage Interfaces: http://www.t10.org
T10, PQI. (2012, 10 9). 2239-D, PCIe(r) architecture Queuing Interface (PQI). Retrieved from T10 Drafts:
http://www.t10.org/drafts.htm#SCSI3_PCI
T10, SAS 2.1. (2011). ANSI/INCITS 478-2011, Serial Attached SCSI - 2.1 (SAS-2.1). Retrieved from
INCITIS: http://www.techstreet.com/standards/incits/478_2011
T10, SAS-3. (Draft 2012, 10 18). T10/2212-D, Serial Attached SCSI - 3 (SAS-3). Retrieved from T10:
http://www.t10.org/drafts.htm#SCSI3_SAS
T10, SOP. (Draft 2012, 9 24). 2239-D, SCSI over PCIe(r) architecture (SOP). Retrieved from T10 Drafts:
http://www.t10.org/drafts.htm#SCSI3_PCI
T10, SPL 2. (2011). ANSI/INCITS 476-2011, SAS Protocol Layer (SPL). Retrieved from INCITIS:
http://www.techstreet.com/standards/incits/476_2011
40
Enterprise SSD Form Factor 1.0a
9 SM-Bus - Informative Appendix
9.1
SM-Bus Vital Product Data (VPD)
Vital Product Data (VPD is stored in an SM-Bus device with a slave address of 0xA6 (i.e., slave address
bits 7-1 correspond to 1010_011 on the SM-Bus). The field definitions align with PCIe Specification field
and capability definitions.
Implementation note: This is likely implemented using a SM-Bus PROM connected to SM-Bus and to
3.3Vaux. This is analogous with DDR’s SPD, using a small PROM to definition the capabilities, starting
with VPD fields followed by a linked list of PROM fields that define what optional “Extended Capabilities”
the Enterprise PCIe SSD supports and the define access details like addresses for extended registers. .
Figure 31: SM Bus Vital Product Data
Addr
0
Function
Class Code
Typ
e
Size
(B)
Default
Value
Description
Controlling Specification
Device type and
programming
interface
PCI Code and ID
Assignment Specification
Rev. 1.0 (PCI-SIG) - Class
Code
PCI-SIG Vendor ID
Serial Number
(vendor unique)
Model Number
(ASCII string)
Enterprise NVMHCI Rev
1.0 - Identify Controller
Data Structure
RO
3
Vendor
RO
2
Vendor
RO
20
Vendor
25
RO
40
Vendor
65
RO
1
Vendor
Maximum Link Speed
RO
1
Vendor
Maximum Link Width
RO
1
Vendor
Maximum Link Speed
RO
1
Vendor
Maximum Link Width
Initial Power
Requirement
s
RO
1
Vendor
RO
RO
1
1
0
0
Maximum
Power
Requirement
s
RO
1
Vendor
RO
RO
1
1
0
0
RO
2
Vendor
3
5
ID
PCIe Port 0
Capabilities
66
67
PCIe Port 1
Capabilities
68
69
70
71
72
73
74
75
Capability
List Pointer
12V power rail initial
power requirement
(W)
Reserved
Reserved
12V power rail
maximum power
requirement (W)
Reserved
Reserved
16-bit address pointer
to start of capability
list (zero means no
capability list)
41
PCIe Base 3.0 (PCI-SIG) Link Capabilities Register /
Maximum Link Speed
PCIe Base 3.0 (PCI-SIG) Link Capabilities Register /
Max Link Width
PCIe Base 3.0 (PCI-SIG) Link Capabilities Register /
Maximum Link Speed
PCIe Base 3.0 (PCI-SIG) Link Capabilities Register /
Max Link Width
Enterprise SSD Form Factor 1.0a
9.2
SM-Bus Enterprise SSD Capability Definitions
The Drive Capability Definitions allow discovery of optional “extended” features or discovery of
implementation variable parameters such as address. These structures in SMbus PROM are optional,
but enumerating the features in this way simplify feature discovery and simplify driver development.
Figure 32 shows the format for Capability Definitions enumerating optional features of an Enterprise PCIe
SSD. The first two bytes identify which capability or feature is implemented. The next two bytes are
pointer to next capability definition (a linked list). A value of “zero” is the end of the linked list. For
features that have parameters such as size or register definitions, these values follow, and the definition
is specific for each capability.
Figure 32: SM Bus Capability Definition
Capability List Headers are 4B in size
Next Capability Address of zero means last capability in list
Byte
3
2
1
0
Next Capability
Capability ID
Address
Optional parameters, implementation values
Standard Capability
Byte
3
2
1
0
Next Capability
0xA5
Address
Vendor Specific
PCI-SIG Vendor ID
Optional parameters, implementation values
Vendor Specific Capability
9.2.1
Dual Port Extended Capability.
Figure 33 shows Capability Definition for Dual Port.
Figure 33: Dual Port Extended Capability Definition
Byte
3
2
Next Capability
Address
Dual Port Capability


1
0
Capability ID = 0xA0
Capability ID value of 0xA0 specifies that Enterprise PCIe SSD support Dual Port Mode as
defined in Section 5.
Next Capability Address is offset to next capability with 0x0 meaning end of capability list.
42
Enterprise SSD Form Factor 1.0a
9.2.2
RefClk Extended Capability.
Figure 34 shows Capability Definition for RefClk.
This is not required for standard RefClk
implementations, but only for Enterprise PCIe SSD that implement extended RefClk capabilities.
Implementation Note: This is providing hooks for future implementations as designs move from current
standard (RefClk required) to new implementation that implement the PCIe SIG change that allow
independent clocking (SRIS ECN - Separate RefClk Independent SSC Engineering Change Notice) (PCI
SIG ECNs, various).
Figure 34: RefClk Extended Capability Definition
Byte
3
2
Next Capability
Address
reserved
RefClk Capability



1
0
Capability ID = 0xA1
RefClk Vector
Capability ID value of 0xA1 specifies that SSD supports extended RefClk functionality.
Next Capability Address is offset to next capability with 0x0 meaning end of capability list.
RefClk Vector is a bit vector decoded as follows: (Set all that apply for a device)
o Bit 0 – 0x01 – Common RefClk required as defined – default.
o Bit 1 – 0x02 – Separate RefClk with no SSC (SRNS)
o Bit 2 – 0x04 – Separate RefClk with SSC (SRIS)
o Bit 3 – 0x08 – Can select Common RefClk pin or Separate RefClk using Vendor specific
mechanism.
o Bit 4 - 0x10 – Will automatically sense RefClk pin and use if provided, otherwise will use
Separate RefClk.
43
Enterprise SSD Form Factor 1.0a
9.2.3
SM-Bus Temperature Extended Capability.
Figure 35 shows Capability Definition for SM-Bus Temperature Sensor.
Implementation Note: This is for an SM-Bus Sensor, and does not enumerate the PCIe in-band sensors
such as temperature reported via SMART structures.
Implementation Note: If a design has multiple SM-Bus temperature sensors, then this Extended
Capability can be repeated.
Figure 35: SM Bus Temperature Extended Capability Definition
Byte
3
2
Next Capability
Address
Temperature Sensor Capability
reserved
Overtemp Threshold







1
0
Capability ID = 0xA2
SM-Bus
Sensor
Address
Type
Warning Threshold
Capability ID value of 0xA2 specifies that a SM-Bus temperature sensor is present.
Next Capability Address is offset to next capability with 0x0 meaning end of capability list.
Sensor Type is decoded as follows
o 0x00 = JC-42.4 TSE2004av compliant temperature sensor on 3.3Vaux
o 0x01 = JC-42.4 TSE2004av compliant temperature sensor on 12V
 The sensor shall implement the features, accuracy, temperature register set, and
behavior of the TSE2004av temperature sensor. Presence of this temperature
sensor shall not imply that TSE2004av EEPROM functionality is available
o 0x02 = JC-42.4 TSE2002av compliant temperature sensor on 3.3Vaux
o 0x03 = JC-42.4 TSE2002av compliant temperature sensor on 12V
 The sensor shall implement the features, accuracy, temperature register set, and
behavior of the TSE2004av temperature sensor. Presence of this temperature
sensor shall not imply that TSE2002av EEPROM functionality is available
SM-Bus Address, bits 1 through 7, specify the SM-Bus slave address of the sensor. A typical
value is 0x36.
Warning Threshold specify the minimum temperature that if read from the temperature sensor
means the PCIe SSD is warning that it is approaching overheating. Additional cooling is
advisable to limit the need for thermal throttling.
Overtemp Threshold specify the minimum temperature that if read from the temperature sensor
means the PCIe SSD is overheating. Accelerated data loss, device shutdown or extreme thermal
throttling may result, addition cooling is required.
The alignment of temperatures is standard for TSE2004av. The temperatures are given in twos
compliment centigrade in bits 2 through 12, with bit 2 representing 0.125ºC, but 11 representing
128ºC, and bit 12 representing twos compliment sign bit.
Implementation Note: The temperatures reported are device specific implementation, and should be
treated as a relative value and used to compare to the Warning and Overtemp, Thresholds. The
temperature is allowed to be measured at some significant or sensitive location on the drive, and does not
have to be the hottest location. Two drives, even from the same vendor, could measure temperature at
different locations in the drive, so comparison of temperature between drives is meaningless.
Implementation Note: If the SM-Bus temperature sensor is connected to 3.3Vaux then to meet the
3.3Vaux power specification of 20µA SM-Bus inactive implies that this temperature sensor is disabled
when 12V is off,
44
Enterprise SSD Form Factor 1.0a
9.2.4
Dual Port and Active/Passive Extended Capability.
Figure 36 shows Extended Capability definition for Active/Passive capability. This is for a partial Dual
Port mode but only one PCIe port is active, but this can be Port A (lanes 0-1, RefClk0, ePERst0#), or Port
B (lanes 2-3, RefClk1,ePERst1#). The default behavior is Port A is Active and if Link training is
successful, then Port-A is used. If Port-A Link training fails Port B is used.
Implementation Note: This is viewed as a transitional step to get partial Dual Port capability before full
dual PCIe controller and dual clocking is supported. This allows the side band interface to force the drive
to use Port B signals. This would be done to force failover to a slave controller.
Figure 36: Dual Port and Active/Passive Extended Capability Definition
Byte
3
2
Next Capability
Address
RefClk Capability
reserved



9.3
1
0
Capability ID = 0xA3
Dual Port
Vector
Capability ID value of 0xA3 specifies that SSD supports extended Dual Port functionality.
Next Capability Address is offset to next capability with 0x0 meaning end of capability list.
Dual Port Vector is a bit vector decoded as follows: (Set all that apply for a device)
o Bit 0 – 0x01 – Dual Port mode as specified.
o Bit 1 – 0x02 – Active/Passive mode
SM-Bus MCTP commands
Not yet defined.
45
Enterprise SSD Form Factor 1.0a
10 System Usage – Informative Appendix
There are multiple standards that use the same family of connectors – SAS and SATA standards, and
emerging standards of Enterprise PCIe SSD (this specification), SATA Express, and SAS. This section
gives an overview of how they interoperate.
SATA Express pin placement is only for reference on how to align this specification’s
Enterprise PCIe pin-out with SATA Express standard (SATA-IO, Draft 2011).
SAS-x4 pin placement is only for reference on how to align this specification’s Enterprise
PCIe pin-out with SAS x4 specification (SFF-8630, 2012).
10.1 Pin usage across standards
Figure 37 show the pin map across SATA and SAS connector to the Enterprise PCIe SSD. Figure 38
shows the pin map across connectors to the Enterprise PCIe SSD. The figures all use the Enterprise
PCIe SSD signal names for consistency.
Implementation Note: There are multiple signals that are similar across the standards that are driven by
system requirements. Even for signals that are logically the same there are multiple copies on the
connector since the source or destination on the system design is not the same.



Existing SATA and existing SAS standards do not share high speed signals with Enterprise PCIe
SSD. Only support signals are shared (12V, GND, PRSNT#, IfDet#). The SAS/SATA/SATA
Express high speed signals are driven by separate SAS/SATA controllers from Enterprise PCIe
ports.
SATA Express and Enterprise PCIe SSD standards do not share similar signals including
separate high speed signals for PCIe lanes. This signal duplication is driven by the upstream
connection. For SATA Express this is the SATA controller typically in a chipset or IO controller.
For Enterprise PCIe SSD this is the highest performance PCIe root ports typically off a CPU or
PCIe fan-out chipset.
o There are two sets of PCIe high speed signals for Lane 0 and 1. The SATA Express PCIe
signals do not use the same wires as the Enterprise PCIe signals. The SATA Express
needs the client PCIe to use the same signals as existing SATA (S1-S7). This allows the
high speed pins to be reused in the cost constrained client systems. The Enterprise PCIe
SSD uses separate signals (E7-E36) since these signals typically go direct to the PCIe
root complex.
o There are independent PCIe Reset signals. SATA Express use pin P2 while Enterprise
PCIe SSD use pin E5. This allows either controller to independently control the link
reset. A controller may drive a reset output to enable simplified device reset.
o There is no PCI RefClk (+/-) for the SATA Express since this is after expected PCIe
changes (a mode for greater skip order set insertion) to allow independent device and
upstream clocking even with spread spectrum clock source.
o The Reserved(WAKE#/OBFF#) PCIe signal is shared, as are shared support 12V, Gnd,
PRSNT#, IfDet#.
SAS-x4 (SFF-8630, 2012) and Enterprise PCIe SSD high speed signals are mixed – some
separate and some shared. This prevents a flexible backplane from supporting Enterprise PCIe
SSDs and SAS-x4 in one board, but connectors are mechanically compatible allowing shared
components.
o The high speed data signals (lanes) are separate for SAS lanes 0-1 but shared for SAS
lanes 2-3.
o SAS-x4 may optionally use new SATA Express support signals such as Reset (P2)
o SAS-x4 may optionally use new Enterprise PCIe SSD support signals such as SM-Bus,
and 3.3Vaux.
46
Enterprise SSD Form Factor 1.0a
o
SAS-x4 may redefine support pins for example layering a second Active (SAS-Active2)
on existing Reserved(WAKE#/OBFF#) signal. If this is done the system must be able to
gate the signal usage based on drive type.
47
Enterprise SSD Form Factor 1.0a
Figure 37: Pin usage across Existing standards
SATA (existing)
SAS (SFF-8680)
Enterprise PCIe (SFF-8639)
Signal names
do not match
SATA spec
S1
S0T+ (A+)
S2
S0T- (A-)
S3
GND
S4
S0R- (B-)
S5
S0R+ (B+)
S6
GND
S7
RefClk1+
RefClk13.3Vaux
ePERst1#
ePERst0#
RSVD
E1
E2
E3
E4
E5
E6
sPCIeRst
3.3V
RSVD(Wake#) P1
P2
IfDet#
Ground
GND
RSVD(DevSLP P3
P4
P5
P6
P7
5V
P8
P9
PRSNT#
P10
Activity
P11
Ground
P12
P13
12 V
P14
P15
Pin
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
E17
E18
E19
E20
E21
E22
E23
E24
E25
Name
RefClk0+
RefClk0GND
PETp0
PETn0
GND
PERn0
PERp0
GND
RSVD
GND
S1T+
S1TGND
S1RS1R+
GND
RSVD
GND
PETp1/S2T+
PETn1/S2TGND
PERn1/S2RPERp1/S2R+
GND
PETp2/S3T+
PETn2/S3TGND
PERn2/S3RPERp2/S3R+
GND
PETp3
PETn3
GND
PERn3
PERp3
GND
SMClk
SMDat
DualPortEn#
Name
Pin
GND
S1
S0T+ (A+)
S2
S0T- (A-)
S3
GND
S4
S0R- (B-)
S5
S0R+ (B+)
S6
GND
S7
RefClk1+
RefClk13.3Vaux
ePERst1#
ePERst0#
RSVD
E1
E2
E3
E4
E5
E6
Pin
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
E17
E18
E19
E20
E21
E22
E23
E24
E25
RSVD(Wake#) P1
sPCIeRst
3.3V
Pin
GND
P2
RSVD(DevSLP P3
IfDet#
GND
Name
P4
P5
Ground
P6
P7
5V
P8
P9
PRSNT#
P10
Activity
P11
Ground
P12
P13
12 V
P14
P15
Name
RefClk0+
RefClk0GND
PETp0
PETn0
GND
PERn0
PERp0
GND
RSVD
GND
S1T+
S1TGND
S1RS1R+
GND
RSVD
GND
PETp1/S2T+
PETn1/S2TGND
PERn1/S2RPERp1/S2R+
GND
PETp2/S3T+
PETn2/S3TGND
PERn2/S3RPERp2/S3R+
GND
PETp3
PETn3
GND
PERn3
PERp3
GND
SMClk
SMDat
DualPortEn#
Name
Pin
GND
S1
S0T+ (A+)
S2
S0T- (A-)
S3
GND
S4
S0R- (B-)
S5
S0R+ (B+)
S6
GND
S7
RefClk1+
RefClk13.3Vaux
ePERst1#
ePERst0#
RSVD
E1
E2
E3
E4
E5
E6
RSVD(Wake#) P1
sPCIeRst
P2
RSVD(ClkReq#) P3
IfDet#
Ground
P4
P5
P6
P7
5V
P8
P9
PRSNT#
P10
Activity
P11
Ground
P12
P13
12 V
P14
P15
Orange=SATA
Purple-SAS
Blue=sPCIe
Light=Optional
Light=Optional
Light=Optional
Gray=unused
Gray=unused
Dark=DaulP
Gray=unused
48
Pin
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
E17
E18
E19
E20
E21
E22
E23
E24
E25
Name
RefClk0+
RefClk0GND
PETp0
PETn0
GND
PERn0
PERp0
GND
RSVD
GND
S1T+
S1TGND
S1RS1R+
GND
RSVD
GND
PETp1/S2T+
PETn1/S2TGND
PERn1/S2RPERp1/S2R+
GND
PETp2/S3T+
PETn2/S3TGND
PERn2/S3RPERp2/S3R+
GND
PETp3
PETn3
GND
PERn3
PERp3
GND
SMClk
SMDat
DualPortEn#
Enterprise SSD Form Factor 1.0a
Figure 38: Pin usage across Emerging standards
SATA Express (Client PCIe)
SAS x4 (SFF-8630)
Enterprise PCIe (SFF-8639)
Signal names
do not match
SATA spec
Name
Pin
GND
S1
S0T+ (A+)
S2
S0T- (A-)
S3
GND
S4
S0R- (B-)
S5
S0R+ (B+)
S6
GND
S7
RefClk1+
RefClk13.3Vaux
ePERst1#
ePERst0#
RSVD
E1
E2
E3
E4
E5
E6
RSVD(Wake#) P1
sPCIeRst
P2
RSVD(ClkReq#) P3
IfDet#
Ground
P4
P5
P6
P7
5V
P8
P9
PRSNT#
P10
Activity
P11
GND
P12
P13
12 V
P14
P15
Orange=SAS,
SATA, SATAe
Light=Optional
Pin
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
E17
E18
E19
E20
E21
E22
E23
E24
E25
Name
RefClk0+
RefClk0GND
PETp0
PETn0
GND
PERn0
PERp0
GND
RSVD
GND
S1T+
S1TGND
S1RS1R+
GND
RSVD
GND
PETp1/S2T+
PETn1/S2TGND
PERn1/S2RPERp1/S2R+
GND
PETp2/S3T+
PETn2/S3TGND
PERn2/S3RPERp2/S3R+
GND
PETp3
PETn3
GND
PERn3
PERp3
GND
SMClk
SMDat
DualPortEn#
Name
Pin
GND
S1
S0T+ (A+)
S2
S0T- (A-)
S3
GND
S4
S0R- (B-)
S5
S0R+ (B+)
S6
GND
S7
RefClk1+
RefClk13.3Vaux
ePERst1#
ePERst0#
RSVD
E1
E2
E3
E4
E5
E6
Pin
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
E17
E18
E19
E20
E21
E22
E23
E24
E25
RSVD(Wake#) P1
sPCIeRst
P2
RSVD(DevSLP) P3
IfDet# (GND)
P4
P5
Ground
P6
P7
5V
P8
P9
PRSNT#
P10
Activity
P11
GND
P12
P13
12 V
P14
P15
Name
RefClk0+
RefClk0GND
PETp0
PETn0
GND
PERn0
PERp0
GND
RSVD
GND
S1T+
S1TGND
S1RS1R+
GND
RSVD
GND
PETp1/S2T+
PETn1/S2TGND
PERn1/S2RPERp1/S2R+
GND
PETp2/S3T+
PETn2/S3TGND
PERn2/S3RPERp2/S3R+
GND
PETp3
PETn3
GND
PERn3
PERp3
GND
SMClk
SMDat
DualPortEn#
Name
Pin
GND
S1
S0T+ (A+)
S2
S0T- (A-)
S3
GND
S4
S0R- (B-)
S5
S0R+ (B+)
S6
GND
S7
RefClk1+
RefClk13.3Vaux
ePERst1#
ePERst0#
RSVD
E1
E2
E3
E4
E5
E6
RSVD(Wake#) P1
sPCIeRst
P2
RSVD(DevSLP) P3
IfDet#
Ground
P4
P5
P6
P7
5V
P8
P9
PRSNT#
P10
Activity
P11
GND
P12
P13
12 V
P14
P15
Purple-SAS
Blue=sPCIe
Light=Optional
Light=Optional
Gray=unused
Dark=DaulP
Gray=unused
Gray=unused
49
Pin
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
S8
S9
S10
S11
S12
S13
S14
S15
S16
S17
S18
S19
S20
S21
S22
S23
S24
S25
S26
S27
S28
E17
E18
E19
E20
E21
E22
E23
E24
E25
Name
RefClk0+
RefClk0GND
PETp0
PETn0
GND
PERn0
PERp0
GND
RSVD
GND
S1T+
S1TGND
S1RS1R+
GND
RSVD
GND
PETp1/S2T+
PETn1/S2TGND
PERn1/S2RPERp1/S2R+
GND
PETp2/S3T+
PETn2/S3TGND
PERn2/S3RPERp2/S3R+
GND
PETp3
PETn3
GND
PERn3
PERp3
GND
SMClk
SMDat
DualPortEn#
Enterprise SSD Form Factor 1.0a
10.2 System Usage Examples
The drive connector supports five interfaces: SATA, SAS (single & dual), SAS X4, SATA Express (Client
PCIe x1-x2 muxed high speed lanes with SATA), Enterprise PCIe x4 (separate high speed lanes). If the
system implementation uses cables to attach to a drive, then all 5 drives types could be supported by
using different flavors of cables and changing the connection at the system end to either SATA/SATA
Express(client PCIe), SAS controller, or Enterprise PCIe x4 root port.
A fixed backplane based configuration (common in servers), the system implementation would have to
select which interfaces to support. The following diagrams show the options:
a. Figure 39 shows a backplane and connections for supporting Enterprise SSD PCIe x4, Client
PCIe (x1-x2) and SATA. (SATA and Client PCIe x2 are muxed).
b. Figure 40 shows a backplane and connections for supporting Enterprise SSD PCIe x4, SAS
(single & dual), and SATA. (SATA and SAS are muxed).
c. Figure 41 shows a backplane and connections for supporting SAS X4, SAS (single & dual), and
SATA. (SATA and SAS are muxed).
Figure 39: Backplane for Enterprise SSD (PCIe x4), SATA & SATA Express (Client PCIe)
Enterprise
PCIe x4
Controller,
Enterprise
PCIe x4
Root port
Storage
Backplane
Enterprise
SSD, and
SATA
(Client PCIe Muxed)
50
SATA
SATA & SATA Express
Enterprise
PCIe
X1-x2
SouthBridge
X4
Controller
New
New
(Client PCIe x1, x2)
New
New
SATA,
SATA Express
Flexible Bays:
Enterprise PCIe or
SATA or SATA Express
SATA
Express
x1-x2
SATA
Not SAS,
not SAS x4
Enterprise SSD Form Factor 1.0a
Figure 40: Backplane for Enterprise SSD (PCIe x4), SAS & SATA
Storage
Backplane
Enterprise
SSD and
SAS
PCIe or SAS or SATA
X4
Not SATA Express
(Client PCIe),
not SAS x4
Enterprise
PCIe
SAS
SAS
SATA
Root port
New
New
Enterprise
PCIe x4
Controller,
New
New
PCIe x4
Flexible Bays
SATA
Expanders
Existing Bays: SAS or SATA
SAS
SAS
SATA
SAS
SAS
SAS
Controller
SAS
SAS
SAS
SATA
Figure 41: Backplane for SAS X4, SAS & SATA
SAS x4
New SAS x4 Bays:
SAS x4, SAS, or SATA
SASx4
New
New
SAS x4
SAS
SAS x4
Controller
SATA
SAS x4
Not Enterprise PCIe,
Not SATA Express
(Client PCIe)
SAS
SATA
Expanders
(Supports SAS, SATA)
SAS
SATA
SAS
SAS
SAS
SAS
51
Existing Bays: SAS or SATA
SAS
SATA
Enterprise SSD Form Factor 1.0a
10.3 Connector Keying (Informative)
The primary goal of connector keying is to make sure that end user pluggable devices and cables can be
keyed to prevent insertion, if the device would not function.
Examples:



Block plugging of a SAS drive into client system with SATA and SATA Express cable.
o Achieved by mechanical keys in region of pin E3-E4.
Block plugging of Enterprise PCIe SSD Cable into a SAS or SATA drive.
o Achieved by cable keying in the alignment posts.
The standard must also support a universal backplane connector that allows any drive to mate.
(Any keying is at the drive carrier or enclosure level.)
SATA Express keying features are only a proposal on how to align this specification’s with proposals for
SATA Express. The SATA Express keying features are not yet standardized, and this document is not
the normative document for SATA Express.
52
Enterprise SSD Form Factor 1.0a
Figure 42 Cross Standard Connector Keying
SATA drive
SATA Express drive
SAS drive
Enterprise PCIe
drive
Enterprise backplane
Workssystem supports
(carrier key)
Worksif system supports
(carrier key)
Worksif system supports
(carrier key)
Works
Works with STP
Mates-Nonfunctional
(requires STP+)
(carrier key)
Works
Mates-nonfunctional
(carrier key)
Works
Works
Blocked-Key
Blocked-Key
Blocked-Key
Blocked-Key
Blocked-Key
Blocked-Key
Blocked-Key
Blocked-Key
Works
Mates-Nonfunctional
(requires STP+)
Works
Mates-nonfunctional
& no detent retention
Works
Blocked-Key
Blocked-Key
Blocked-Key
Works
Blocked-Key
Blocked-Key
Blocked-Key
SAS backplane
SATA Express
backplane/laptop
SATA backplane/laptop
Works
Enterprise cable
SAS cable
SATA Express cable
SATA cable
Key:
Works
Works as expected
Works with STP
Works as expected since SATA Tunnel Protocol widely deployed
Works if system supports
Connectors will mate, will work if system designed to support - Section 10.2
Blocked-key
Connectors do not mate, blocked by connector keying features
Colored light green because this is desired behavior
Mates-nonfunctional
Connector will mate, but will not function.
Carrier key
Disk carrier is used, and system could be designed to prevent insertion
53
Enterprise SSD Form Factor 1.0a
11 Specification Conventions
11.1 Definitions
11.1.1 PCI Express® (PCIe)
PCIe refer to the PCIe Express IO bus standards. Please see the 8.1 References on page 39 for a list of
the most relevant PCIe documents (PCI SIG, various).
11.1.2 PCI Express® Generation 2 (PCIe Gen2)
In this context Gen 2 is used to refer to a link speed of 5Gbps using 8b/10b encoding.
11.1.3 PCI Express® Generation 3 (PCIe Gen3)
In this context Gen 3 is used to refer to a link speed 8Gbps using a 128/130 encoding with scrambling.
11.1.4 PCI Express® x4 (PCIe x4)
x4 means using 4 PCIe lanes for communication. This is 4 differential pairs in each direction. Total
signals is 4 lanes times 2 (differential) times 2 (Transmit and receive) = 16 signals.
11.1.5 SFF standards
Small Form Factor Committee is an ad hoc group that defined the 2.5” & 3.5” drive and related
specifications. Documents created by the SFF Committee are submitted to bodies such as EIA (Electronic
Industries Association) or an ASC (Accredited Standards Committee).
Please see the 8.1 References on page 39 for a list of the most relevant (SFF, various).
11.1.6 SSD
Solid State Disk.
11.2 Keywords
Several keywords are used to differentiate between different levels of requirements.
11.2.1 mandatory
A keyword indicating items to be implemented as defined by this specification.
11.2.2 may
A keyword that indicates flexibility of choice with no implied preference.
11.2.3 optional
A keyword that describes features that are not required by this specification. However, if any optional
feature defined by the specification is implemented, the feature shall be implemented in the way defined
by the specification.
11.2.4 R, RSVD
“R” and RSVD are used as an abbreviation for “reserved” when the figure or table does not provide
sufficient space for the full word “reserved”.
11.2.5 reserved
A keyword indicating reserved signal pins, bits, bytes, words, fields, and opcode values that are set-aside
for future standardization. Their use and interpretation may be specified by future extensions to this or
other specifications. A reserved bit, byte, word, field, or register shall be cleared to zero, or in accordance
with a future extension to this specification. The recipient shall not check reserved bits, bytes, words, or
fields.
54
Enterprise SSD Form Factor 1.0a
11.2.6 shall
A keyword indicating a mandatory requirement. Designers are required to implement all such mandatory
requirements to ensure interoperability with other products that conform to the specification.
11.2.7 should
A keyword indicating flexibility of choice with a strongly preferred alternative. Equivalent to the phrase “it
is recommended”.
55
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