RA60_RA80_And_RA81_Disk_Drives_Brochure_Aug82
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THE RA60, RA80 AND RA81 DISK DRIVES
AND THE DIGITAL STORAGE ARCHITECTURE
Digital Equipment Corporation • Colorado Springs, Colorado
August 1982
Copyright, © Digital Equipment Corporation, 1982
Digital Equipment Corporation makes no representation that the interconnection of its products in
the m:ltter described herein will not infringe existing or future patent rights, nor do the descriptions
contained herein imply the granting of licenses to make, use or sell equipment or software constructed
or drafted in accordance with the description.
The following is for information only and is subject to change without notice by Digital Equipment
Corporation. Furthermore, Digital assumes no responsibility for any errors which may appear herein.
The major trademarks of Digital Equipment Corporation are:
DEC
DECUS
DECMATE
DECnet
PDP
UNIBUS
VAX
VT
DECsystem-IO
DECSYSTEM-20
DECwriter
DIBOL
EduSystem
PDT
lAS
MASSBUS
WORKPROCESSOR
RSTS
RSX
VMS
OMNIBUS
Patents are pending on the UDA50 Controller, the RA60 Disk Drive, the RA80 Disk Drive, and the
RA81 Disk Drive.
i i
THE RA60, RA80 AND RA8) DISK DRIVES
AND THE DIGITAL STORAGE ARCHITECTURE
PAGE
T ABLE OF CONTENTS
INTRODUCTION
1
The Digital Storage Architecture (DSA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
The DSA Product Family ...................................................... 1
The Product Family and the Architecture ......................................... 1
State-of-the-Art Technology .................................................... 3
Price Comparison ............................................................ 3
Shopper's Guide to Disk Subsystems ............................................ 4
DIGITAL STORAGE ARCHITECTURE (DSA)
5
Architecture Overview ........................................................ 6
Host-to-Controller Interface .................................................... 7
Controller-to-Disk Interface .................................................... 10
DSA SUBSYSTEMS
Throughput Enhancement Features ..............................................
Data Integrity Features ........................................................
Availability Enhancement Features ..............................................
DSA Subsystem Features Vis-A-Vis Competition ..................................
13
13
14
16
18
UDA50 DISK CONTROLLER
19
UDA50 Operation and Hardware ................................................ 20
THE RA60: THE REMOVABLE MEDIA SOLUTION
23
Features Summary ............................................................ 24
RA60 Disk Drive Features ..................................................... 25
THE RA80: ENTRY LEVEL DSA DISK
27
Features Summary ............................................................ 28
RA80 Disk Drive Features ..................................................... 29
THE RA81: THE LOWEST COST PER MEGABYTE SOLUTION
31
Features Summary ............................................................ 32
RA81 Disk Drive Features ..................................................... 33
SPECIFICATIONS SUMMARY
35
UDA50 Specifications ........................................................ 35
RA80, RA81, RA60 Specifications Summary ..................................... 36
iii
RAa 1 DISK DRIYE
• 456 Mb Fi,ced Media Disk
• $26,000 Subsystem ($ 120 BMC)
• $ J 9,000 Add·On ($90 BMC)
• Type, DiSCountable
RAao DISK DRIYE
• J 2 J Mb Fixed Media Disk
• $2 J,000 Subsystem ($ 1 J J BMC)
• $14,000 Add·O n ($al BMC)
•
Type I D;scountable
• 205 Mb Removable Media D;sk
• $22,000 Sybsystem ($ 1 10 BMC)
• $, 5,000 Add·O n ($ao BMC)
• Type I DiSCOuntable
RAa J TRIPLE DRIYE OPTION
• J.4 Billion Bytes
• $55,000 Subsystem ($300 &MC)
• $50,000 Add·On ($270 BMC)
• Type I Discountable
INTRODUCTION
The Digital Storage Architecture (DSA)
A megabyte of disk storage that cost over $1 ,000 ten years ago costs under $40 today - a consequence of
increased recording qensities. But there are other consequences: High density disks require controllers that
accommodate high transfer rates and technologies that protect against media defects which can otherwise
corrupt databases. Your subsystem could be limited to yesterday's disk technology and yesterday's disk prices!
At Digital, we design both disk drives and controllers, and hence understand the subsystem requirements
to take advantage of evolving disk technologies. In order to optimize data integrity, throughput and availability,
as well as to provide flexible, expandable, migratable products, Digital has taken an architectural approach to
storage subsystem design, fittin·g the products into a framework which will remain constant across product
generations. Like the V AX architecture for computer systems, the Digital Storage Architecture (DSA) is the
storage architecture for the Eighties.
The DSA Product Family
The RA60, RA80 and RA81 disks and the UDA50 controller are the first members of the DSA Product
Family which feature:
•
•
•
•
•
•
Standardized hardware interconnect and software protocols
A single operating system driver and set of utilities
Throughput, data integrity and availability features
Industry leading capacities for rack mounted disks
Up to three drives per cabinet - mix and match flexibility
Low lifetime cost of ownership
The DSA family is the only state-of-the-art 100 to 1400 megabyte product set which offers hoth
Winchester fixed media and removable media technologies to service diverse applications.
The Product Family and the Architecture
Industry leading performance features as well as superior space effi~iency alld cost of ownership are why
DSA subsystems are the smart decision for your present systems. The architectute'is why a smart decision today
will prove to be an even better decision in the future.
System Support
The DSA products are initially available on selected systems. Consult your Digital Sales Representative
for information.
UDA50 - The Intelligent Controller
UDA50 subsystems lead the industry in comprehensiveness and
power of data integrity features. A break-through data error correction
system corrects multiple error bursts totaling up to 80 bits. The UDA50
accelerates throughput by performing multiple levels of performance
optimization. Radial interconnects, microdiagnostics in every subsystem component, and standard dual access provide outstanding availability. If you thought subsystems were all alike, the UDA50 is something new to think about!
RA80 Disk - The Lowest Cost Solution
The price-reduced RA80, the entry level member of the family, has
121 megabytes of formatted user capacity. The Winchester RA80, and
removable media 10 megabyte RL02 subsystem, is the complete storage
solution for a 100 to 200 megabyte database.
RA60 Disk - The Removable Media Solution
The RA60 is the industry's highest capacity and lowest price-permegabyte rack mounted, removable media disk. With 205 megabytes of
user formatted capacity, 615 megabytes are available in a 42-inch high
cabinet - 500/. more than any other removable media product. The
RA60 provides 205 megabytes of removable media flexibility for
$15,000.
RA81 Disk - The Lowest Cost Per MB Solution
The Winchester RA81, the industry's highest capacity rackmounted disk drive, defines new frontiers in data storage - 456 megabytes of user formatted capacity in a 10.4-inch high enclosure. Almost
1.4-billion bytes are available in a waist-high cabinet, about 250 megabytes per square foot of floor space. The RA81 provides 456 megabytes
of reliable Winchester disk capacity for $19,000 or, for real economy,
the triple-drive option for $50,000.
2
State-of-the-Art Technology
The obvious path to leadership products is state-of-the-art technology. With disks, the challange is
advancing in both areal density, the key metric of disk technology, and data reliability. The RA60 and RA80
areal density numbers speak for the themselves (refer to the charts below). But to achieve areal density, we
didn't compromise data reliability: We enhanced it with embedded servo positioning technology and a
comprehensive set of data protection features.
INDUSTRY FRONTIER
AREAL DENSITY (8ITS PER SQUARE INCH) VERSUS TIME
15M
INDUSTRY FRONTIER
AREAL DENSITY (8ITS PER SQUARE INCH) VERSUS TIME
10M
10M
A
R
E
A
L
8M
A
R
E
A
L
6M
D
E
N
S
I
T
Y
4M
8M
6M
D
E
N
S
I
T
Y
4M
2M
2M
1972
1974
1978
1976
1980
1972
1982
1974
1976
1978
1980
1982
Price Comparison
The RA60, RA80, and RA8! define a new price-per-megabyte frontier for system suppliers. What is even
better, Digital is the only supplier to offer both state-of-the-art removable and Winchester fixed media disk
drives. The chart below shows how Digital stacks up against its closest system competitors.
$150
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* Triple Drive Option
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200-400MB
II
400 -
CAPACITY RANGES
3
..
1200 MB
..
..
1200 MB & UP
Shopper's Guide to Disk Subsystems
Cost of Ownership
Some subsystems are cheap to buy but expensive to own. DSA
subsystems not only carry low hardware price tags but also low
maintenance prices. Compare lifetime cost of ownership.
Actual Capacity
Some disk suppliers advertise gross, unformatted capacity that includes a significant amount of space unavailable for user data. The
advertised capacities on DSA disks are 100% available for user data.
In addition, since all DSA disks have space reserved for replacement
blocks, user capacities never shrink.
Data Integrity
How much does it cost you to reconstruct a file because the subsystem
cannot find or cannot read a block of data? That is why DSA
subsystems include the industry's most comprehensive set of data
protection features.
I/O Throughput
Look at the disk specifications and then look more carefully at the
subsystem performance optimization features. Seek ordering, overlapped seeking and rotational optimization in DSA subsystems significantly. increase throughput.
Subsystem Availability
System downtime is disruptive, frustrating and expensive. High
reliability, automatic self-testing and fault isolating microdiagnostics
are built into every DSA disk and controller. Our radial interconnect
prevents a problem in one disk from affecting the operation of other
disks.
Ex tra Charges
A removable media disk is not very useful without a pack, nor a
subsystem without cabinetry and cabling. With some products these
are expensive optional features. In DSA products, not only are these
standard, but so is drive dual access. Purchase a second I/O cable,
and your DSA disk can be shared between two controllers.
4
DIGITAL STORAGE ARCHITECTURE (DSA)
The software, controller and disk technologies involved in data management and storage advance at
different rates. Our storage architecture decouples these technologies to allow advancements to be easily,
quickly and non-disruptively incorporated into our product set. Ten reasons make the Digital Storage
Architecture the standard for comparison.
Reason # 1 - Solid Data Integrity
Features:
• 170 bit error correction code (ECC)
• New error detection code (EDC)
• Address verification system
• Seek error recovery and parity checking
• Automatic sector retirement system
• Improved disk mapping system
• Data compare and access commands
• Multi-block transfer control
• Autocorrelated synchronization
Reason #2 - High I/O Throughput
Features:
• Command queue for seek ordering
• Express queue for FIFO service
• Overlapped seeking
• Rotational optimization
• Speed matching buffer and DMA transfers
• Direct revectoring system
Reason # 3 - Improv~d System Availability
Features:
• Radial interconnect with bus isolation
• On-board microdiagnostics
• Console fault display
• Off-line repair and remote diagnostic support
• Power-up verification
• Dual access as a standard feature
5
Reason #4 -
Off-Loading of the Host System
Feature:
• Throughput, data integrity and availability are the responsibility of the subsystem and are
provided at no cost in host system overhead.
Reason # 5 -
Lower Lifetime Cost of Ownership
Feature:
• Balanced integration of hardware, software and reliability features focused on lowering the
total cost of buying, installing and maintaining subsystems.
Reason #6 -
Hardware/Software Independence
Features:
• New controllers can be introduced without requiring a new disk class driver in the host system.
• New disks can be introduced without requiring any changes to either the host system software or
the subsystem controller.
Reason #7 -
Support for New Technologies
Features:
• Supports higher disk transfer rates.
• Accommodates increased media defects associated with higher disk areal densities.
• Automatically adapts to disk drive specific geometries.
Reason #8 -
Migratable Products
Features:
• Standard
• Standard
• Standard
• Standard
• Standard
Reason #9 -
host-to-controller protocol
controller-to-disk protocol
controller-to-disk hardware interconnect
med;a format
diagnostics and utilities protocol
Increased Functionality and Ease of Use
Features:
• Disks appear as perfect logical volumes to the host
• Subsystem handles logical-to-physical translation
• New data compare, erase and access commands
• Alternative I/O request servicing facilities
Reason # 10 -
Support for a Wide Range of Products
Features:
• Varying disk capacities with different transfer rates
• Removable media and Winchester fixed media technologies
Architecture Overview
•
Host-to-Controller Interface - Two layers of software define the host system-to-controller interface.
Class drivers perform generic disk functions and communicate with the controller via message packets.
Port drivers provide the communication protocol to send and receive message packets over a specific
communications bus.
• Controller-to-Disk Interface - The Standard Disk Interface (SDI) defines the hardware interconnect
and communications protocol between the SDI driver in the controller and the SDI driver in the disk
drives. The Digital Standard Disk Format partitions physical disk space into logical areas for user data,
replacement blocks, format control tables and diagnostic tests.
6
THE ARCHITECTURE
LAYER
COMPONENT
MAJOR SEGMENTS
OPERATING SYSTEM
HOST
DISK
CLASS
DRIVER
DUP
CLASS
DRIVER
UNIBUS
PORT DRIVER
SERIAL BUS
PORT DRIVER
HOSTCONTROLLER
HOST
INTERCONNECT
PORT DRIVER
CONTROLLER
SERVER
SDI DRIVER
DISK
INTERCONNECT
DISK
SDI
_.....
ts:DRI~
I
DIGITAL
CONTROLLERDISK
)
STANDARD
DISK FORMAT
Host-to-Controller Interface
The host system uses two levels of software to accomplish I/O operations. The higher level, named class
drivers, performs generic functions (such as reading and writing) to classes of devices (such as disks). The class
driver's knowledge of a disk is limited to a logically perfect storage device with a fixed linear address space.
The controller determines and translates specific disk geometries into error free logical block capacity and
passes this information to the class driver. The class drivers are independent of the specific characteristics of the
communications bus, the controller and the storage devices. Class drivers communicate with the controller's
servers via message packets.
The lower level of host system software, named port drivers, passes the message packets along the
communications bus. Port drivers operate with a specific communication bus and are unaware of the meaning
of the messages. In UDASO-based subsystems, the UNIBUS provides the communications path between the
port drivers.
7
In the controller, there are two corresponding levels of software. The higher level of software is named the
server. The UDA50 has two servers - the Mass Storage Control Protocol (MSCP) Server and the Diagnostics
and Utilities Protocol (DUP) Server. The servers constitute the intelligence of the controller and, therefore,
define the functionality of the subsystem. The lower level of software is also a port driver and functions
analogously to its counterpart in the host system.
.... - - - - .....
Indicate physical communications
Indicate logical communications
UDA50 CONTROLLER
HOST
I
CLASS
DRIVER
PORT
DRIVER
~
~----------
14--
f-------------
MSCP AND DUP
~~
SERVER
I
COMMUNICATIONS
PROTOCOL
----
PORT
DRIVER
~
,
PORT
PORT
UNIBUS COMMUNICATIONS LINK
Disk Class Driver and MSCP Server
The disk class driver in the host system uses the Mass Storage Control Protocol (MSCP) to communicate
with the MSCP server in the UDA50. MSCP is a message based protocol which defines those functions generic
to disks. Hence, new controllers and new disk drives do not require changes to the disk class driver. MSCP has
commands for performing I/O transfers, controlling devices and obtaining status. Three types of communication services are used between the disk class driver and the MSCP server:
• A sequential message communication service used for MSCP control messages.
•
A block data communication service used to move data between the host system and the UDA50
controller.
•
A datagram communication service used for error log messages.
The MSCP server performs the following functions:
• Determines the number of disks in the subsystem, their type and number of logical blocks, their
availability and status, and communicates this information to the disk class driver.
• Receives and optimizes I/O requests, performs the requests, transfers data between the host system and
the disks, and buffers the data transfers as necessary.
• Translates between logical addresses in I/O requests and physical addresses on disks.
•
Performs error detection and recovery, and reports any significant errors to the host system.
Since the disk class driver is only concerned with the number of logical blocks on a disk, new disk drives
can be introduced without requiring any changes to the host system software.
8
HOST
MSCP
CLASS
DRIVER
~
__
~SCP_ _
1__
PROTOCOL
UDA
MSCP
SERVER
.~
,
UNIBUS
PORT
DRIVER
,
UNIBUS PORT
f4--- ~------ PROTOCOL
.......
UNIBUS
PORT
DRIVER
•
,
,
UNIBUS
DUP Class Driver and DUP Server
The Diagnostics and Utilities Protocol (DUP) is the method of communicating between the host system
and the DUP server in the controller. Using this protocol, the host system may request the server to load and
execute a diagnostic or a utility supplied by the host system. DUP provides mechanisms to do the following:
• Load controller-resident remote programs from the host
• Communicate with the controller-resident remote program
• Provide host-resident virtual terminal services
• Make progress inquiries to the server
• Terminate the program
• Run and monitor controller resident utilities or diagnostics
The advantage of this approach is that only one set of diagnostics and utilities (that run in the controller)
need be developed, no matter how many host computer operating systems support the controller. The host
based DUP code is the only software that needs to be unique to a specific operating system or host computer.
Two types of communications services are used across the connection between the DUP class driver and
DUP server.
• A sequential message communication service used for DUP control messages.
• A block data communication service used to move data between the host system and the controller.
HOST
DUP
CLASS
DRIVER
UDA
~
DUP
f--------
f-~
PROTOCOL
DUP
SERVER
~
,
PORT
DRIVER
,
- - - - - f--.
f4--- - -PROTOCOL
UNIBUS PORT
~
UNIBUS
9
PORT
DRIVER
Port Drivers
Port drivers, resident in both the host system and controller, are the interface between the host system and
controller. The port drivers:
1.
Supply information for verifying correct operation of the subsystem controller during initialization.
2.
Minimize host interrupts during peak I/O load periods.
The port consists of two layers.
1.
The Transport Layer: This is the physical communications bus for the bi-directional transmission
of data and control signals.
2.
The Logical Layer: This is a set of rules and procedures implemented in the host and the controller.
The tasks of the logical layer are the exchange of control messages and the verification of correct
operation of the transport mechanism.
The port's logical layer is implemented as a set of data structures in host memory which are operated on by
both the host system and the subsystem controller according to a set of rules.
The UNIBUS port architecture uses interrupts and UNIBUS I/O page registers for the operation of the port
but not directly for the I/O devices attached to the controller. The port design assumes a command/response
relationship. The actual transmission of commands and responses is affected by the port via DMA transfers to
and from a communication region in host system memory. The port polls this region for commands; the host
system polls it for responses. From the viewpoint of the host system, an I/O operation begins when it deposits a
command descriptor in the command ring. When the operation is complete, the corresponding response packet
is removed by the host system from the response ring.
Controller-to-Disk Interface
The controller-to-disk interface is defined by the Standard Disk Interface which specifies the hardware and
software interconnect as well as the format of the media.
HOST
'CPU
PORT
I
HOST INTERCONNECT
STORAGE
CONTROLLER
"-
Standard Disk Interface (SDI)
The SDI consists of three components:
• SDI bus
• SDI protocols
• Digital Standard Disk Format (DSDF)
10
"'-
"SOl
SDI Bus
The SDI bus is a radial drive-to-controller interconnect with a maximum length of 80 feet (30 meters).
Hence, for multi-drive subsystems, SDI buses are configured in parallel to prevent a failure in one drive from
affecting operation of other drives. The bus is a four line coaxial cable:
• Controller-to-drive data and control
• Drive-to-controller data and control
• Controller-to-drive status information
• Drive-to-controller status and attention information
C
0
N
T
R
0
L
L
E
R
--
CONTROLLER STATE
--
DRIVER STATE
--
CONTROLLER CMD/DATA
--
DRIVE RESPONSE/DATA
D
R
I
V
E
SDI Protocol
The SDI provides the following commands:
• Obtain disk drive parameters (retry counts, timeouts, error thresholds, etc.) and geometry characteristics (sectors/track, number of tracks, number of cylinders, etc.)
• Obtain and release drives, spin up/down, get drive status, etc.
• Read, write, and format drives
Digital Standard Disk Format (DSDF)
DSDF defines how a physical disk is partitioned into logical areas. The disk is formatted to contain four
logical areas: The user area, the diagnostic test area, replacement block area and the format control table area.
The bad block replacement strategy provides error free virtual user space and a means of identifying
correctly written but logically incorrect sectors. One replacement block is reserved on every track on the disk
for improved performance. The Format Control Table provides a master list of media defects. The diagnostic
test area is reserved for diagnostic reading and writing to the disk. This area is physically separated from user
data space by several cylinders.
LOGICAL BLOCKS
(LBN)
HOST
APPLICATIONS
I
I
I
APPLICATIONS
r--------
DIAGNOSTIC BLOCKS
(DBN)
FORMAT
CONTROL
TABLES
DIAGNOSTIC
CYLINDERS
REPLACEMENT
AND
CACHING'
TABLES
REPLACEMENT
BLOCKS
(RBNs)
I-- VISIBCEW
HOST
EXTERNAL BLOCKS
(XBNI
~
J
VISIBLE TO HOST
OPERATING SYSTEM
VISIBLE TO CONTROLLER
11
NOTES
DSA SUBSYSTEMS SUPERIOR THROUGHPUT, DATA INTEGRITY, AND A VAILABILITY
DSA subsystems provide significant improvements in:
•
•
•
I/O throughput
Data integrity
Subsystem availability
Throughput Enhancement Features
I/O throughput as seen by the user is more dependent on performance optimization features than
performance related disk specifications. In DSA subsystems, the optimization algorithms in the UDA50
significantly enhance I/O throughput. A buffer memory in the UDA50, named the command queue, stores up
to twelve I/O requests from the host system. Firmware controlled operations on the command queue optimize
disk accesses and data transfers without imposing any overhead burden on the host system.
Seek Ordering
I/O requests in the command queue are logically sorted into individual queues by disk volume. The I/O
requests are reordered by an elevator algorithm and executed by cylinder address rather than in the order
received from the host system. The command queue is dynamically updated as new requests are received. A
fairness counter prevents any disk from monopolizing the I/O channel.
BENEFIT
Seek ordering can dramatically improve throughput in single drive
systems (up to 35% improvement has been observed), as well as in
multiple drive systems.
Express Queueing
First-in, first-out (FIFO) servicing of I/O requests can be specified through a mechanism named the
express queue. In addition, FIFO servicing can be specified for some requests and seek ordering for others.
BENEFIT
Provides the flexibility to select the request servicing that will
optimize throughput.
Overlapped Seeking
The UDA50 initiates simultaneous seek operations to all disks in the subsystem with an I/O request in the
command queue. One drive can perform a data transfer while other drives are seeking.
13
BENEFIT
Overlapped seeking provides a major throughput improvement in
multiple drive systems.
Rotational Optimization
When multiple disks are simultaneously positioned on requested cylinders, the UDA50 selects the drive
nearest its beginning sector to perform a data transfer.
BENEFIT
Rotational optimization provides an incremental throughput improvement in multiple drive systems that employ overlapped
seeking.
Speed Matching Buffer
The UDA50 contains twelve sectors of RAM memory that allow disk-to-controller transfers to occur at
higher speed than controller-to-host system transfers.
BENEFIT
The deep UDA50 buffer improves performance by minimizing
missed disk revolutions due to a buffer full condition.
Direct Revectoring System
When a retired sector is encountered, the drive automatically references the replacement sector which
generally is located on the same track.
BENEFITS
The direct revectoring system avoids wasting time reseeking to a
look-up table to determine the address of replacement sectors.
Also, since file structures never have to be rearranged to accommodate bad blocks, disks can be backed up and restored with a high
speed vol ume copy.
DMA Transfers
Data is transferred directly to and from host system memory.
BENEFITS
System throughput is improved by avoiding interrupts to transfer
data.
Data Integrity Features
The UDA50 controller has the most powerful and comprehensive set of data integrity features in the
industry. Most manufacturers specify that unrecoverable errors (data loss) can occur as often as every time 1012
or 1013 bits are read. By contrast, it is unlikely that data loss will ever occur with properly functioning DSA
subsystems. This level of data protection is accomplished without imposing any overhead on the host system.
All UDA50 recovery operations are initiated and completed in the subsystem.
170-bit Error Correction Code (ECC)
In write operations, the UDA50 calculates a I70-bit ECC which is written in the sector postamble. On read
operations, the UDA50 checks the ECC to verify that the data is correct. The ECC will detect all errors and
correct: (A) A single error burst up to 80 bits; or (B) up to eight independent one-to-ten bit error bursts.
BENEFIT
Loss of data due to uncorrectable data errors caused by media
degradation is virtually eliminated. The I70-bit code is far more
powerful than conventional 32-bit ECC which only corrects up to
an II-bit single error burst.
14
Error Detecting Code (EDC)
As data is received from host system memory, the UDA50 calculates a code corresponding to each word
and accumulates the codes. The result, named write EDC, is written on the disk in the sector postamble. On
read operations, the same process occurs in reverse as data is sent to host memory and a read EDC is calculated.
The write and read EDCs are compared and a retry is automatically initiated if a miscompare occurs.
BENEFIT
Undetected (and hence uncorrected) errors due to a controller
malfunction are virtually eliminated. In addition, the EDC verifies
proper functioning of the ECC hardware by catching ECC errors.
Memory Parity
The UDA50's RAM and ROM memories include parity checking.
BENEFIT
Parity checking detects single bit memory errors. (Note: The EDC
detects multiple bit memory errors occurring in the data buffer and
causes the controller to retry the operation.)
Address Verification System
In the header preamble of each sector, four copies of the address are recorded. On read operations, the
UDA50 compares the four copies and requires only a single match between two of the four copies to verify that
the sector address was correctly written and read.
BENEFIT
Loss of data due to header errors caused by media defects is
virtually eliminated. The UDA50's address verification system
outperforms conventional CRC systems which only provide address error detection capability.
Seek Error Recovery System
After validating the sector address read from the disk, the UDA50 compares this address to the requested
address retained in the UDA50 memory. If a miscompare occurs, the UDA50 will automatically reinitiate the
seek operation.
BENEFIT
The UDA50 detects mispositioning errors by verifying cylinder,
track and sector address. (Note: DSA disks also provide for seek
error recovery by verifying cylinder and head selection).
Error Logging and Automatic Sector Retirement System
During initialization, DSA disks provide to the UDA50 two error severity thresholds for: (A) Reporting
recoverable errors to the operating system error log; and, (B) retiring the sector. The UDA50 compares data
errors against both thresholds. If the severity of an error exceeds the lower threshold, it is reported to the host
system error log. If it exceeds the higher threshold, the UDA50 reports the error and requests authorization from
the operating system to retire and revector the sector to a replacement sector.
BENEFIT
Sectors are retired before the phenomenon of error propagation
causes recoverable errors to become unrecoverable errors and
hence cause data loss.
Disk Mapping System
The UDA50 performs logical-to-physical sector address translation. A quadruplicated header code
identifies active and retired sectors. In the case of retired sectors, the code specifies the alogorythm to revector
to the replacement sector which is generally located at the end of the same track or on an adjacent track .. The
UDA50 processes this information and automatically revectors to the replacement sector. As a failsafe
procedure, revectoring addresses are also copied in a look-up table stored on the disk.
15
BENEFIT
The mapping system virtually eliminates data loss caused by
revectoring errors as well as improves performance by generally
avoiding seeks to a look-up table for revectored addresses.
Data Compare Commands
The MSCP protocol provides commands to perform read and write compares as well as to compare host
memory data with data on a disk.
BENEFIT
Provides an additional level of data integrity.
Access and Erase Commands
The MSCP protocol provides an access command to perform surface checking to determine if any media
degradation has occurred and an erase command to eliminate files.
BENEFIT
The access command verifies that sectors are error free and the
erase command provides for data security.
Multi-Block Transfer Control
The UDA50 controls the data transfers from the disk to the speed matching buffer in the UDA50. If a data
transfer involving a high number of sectors causes a buffer-full condition, the UDA50 will suspend the transfer
and automatically resume it when buffer space becomes available.
BENEFIT
Eliminates the occurrence of UDA50 data-late errors and the
associated need for retry operations.
Autocorrelated Synchronization Character
An autocorrelated sync character preceeds a data transfer between a DSA disk and the UDA50. The
autocorrelation mechanism allows synchronization even if up to three bits in the sync character are in error.
BENEFIT
Minimizes the occurrence of sync byte errors which require retry
operations. This mechanism outperforms conventional synchronization systems that cannot tolerate even single bit errors.
Availability Enhancement Features
The UDA50 and DSA disk drives offer a set of high-availability features not typically found in other disk
subsystems. These features, together with high MTBF hardware, provide high system uptime and low
maintenance prices.
Radial Interconnect
DSA subsystems have a point-to-point interconnect between each disk and the UDA50 controller for data
as well as control and status information.
BENEFIT
Improves system uptime because a drive can be logically isolated
from the subsystem and repaired without disrupting the operation
of other drives in the subsystem.
On-Board Microdiagnostics
All DSA drives and the UDA50 controller contain a comprehensive set of fault-isolating diagnostics
which isolate over 80% of all failures to a single field replaceable unit.
BENEFIT
High diagnostic fault isolation capability decreases mean time to
repair (MTTR). Most failures can be diagnosed and repaired in less
than one hour. No special test equipment is needed.
16
Console Fault Display
In DSA disks, a fault causes illumination of the fault console light. By depressing the fault console light
switch, a code will be displayed via illumination of other console lights. The code iden tifies the failure class.
BENEFIT
This information allows most failures to be quickly diagnosed and
identifies the required replacement part.
Remote Diagnostic Support
The microdiagnostics can be operated: (A) Locally with the drive off-line; (B) locally with the drive
on-line through the system console; or, (C) remotely with the drive on-line through Digital's diagnostic service.
BENEFIT
The remote diagnostic service insures that field engineers are
dispatched with the correct replacement parts.
Power-up Verification
Functional tests which include reading and writing on reserved diagnostic cylinders, run automatically
during power-up and initialization.
BENEFIT
Power-up verification prevents initiating a job stream with a malfunctioning drive. This is especially important in certain classes of
applications such as a real-time process control.
Dual Access
All DSA disks have dual access logic as a standard drive feature. Port switches on the drive console allow
the drive to be dedicated to a single UDA50 or statically shared between two UDA50s. Static sharing implies
that one UDA50 cannot access a disk that is already in the process of accessing or transferring data to another
UDA50. Static dual access is provided primarily for high availability as opposed to high performance switching
of disks between systems.
BENEFIT
Dual access provides the redundancy required for high availability
systems, or, it can be used to share disks between systems. In DSA
subsystems, only the purchase of a second I/O cable is required to
connect a DSA disk to a secondUDA50 controller.
Bus Isolation
Pulse transformers on the drive-to-controller I/O cable provide for electrical isolation between subsystem
components. The I/O cable plugs into bulkhead connectors on the disk and CPU cabinets.
BENEFIT
Systems can be quickly and easily reconfigured without concern
for ground loops caused by different power sources.
Last Fault Register
The UDA50 contains an error register that is dynamically updated.
BENEFIT
The last fault register is used as a troubleshooting aid.
17
DSA Subsystem Features Vis-A-Vis Competition
DSA
Subsystems
Typical
Competitive
Subsystems
Yes
Yes
Yes
Yes
12 sectors
Yes
Yes
No
Yes
Yes
No
3 sectors
No
Yes
80 bits
8 bursts
Yes
Detection/
Correction
Yes
Yes
11 bits
1 burst
No
Detection
Yes
Yes
Yes
No
No
No
Yes
No
Interconnect
Radial
On-board diagnostics
Remote diagnostic
Support
Power-Up check-out
Dual access
Bus isolation
UDA50 & dri ves
Radial/Daisy
chain
Controller only
Yes
UDA50 & drives
Standard
Yes
No
Controller only
Optional
No
Yes
3 MB/sec
Yes
No
1.2 MB/sec
No
Features
Throughput features:
Seek ordering
Express queue
Overlapped seeking
Rotational optimization
Speed matching buffer
Direct revectoring system
DMA transfers
Data integrity features:
ECC capability:
Max. error bits
Max. error bursts
EDC
Address verification
Seek error recovery
Disk mapping system
Multi-block transfer
control
Data compare commands
Access command
Autocorrelated
synchronization
Yes
No
A vailabil ity Features:
Other Features:
System off-loading
Max. disk data rate
Software independence
18
UDA50 DISK CONTROLLER
The UDA50 is the first controller implementation of the Digital Storage Architecture (DSA). It connects
up to four DSA disks via the radial SDI interconnect to Digital systems (see diagram below). Many controllers
limit systems to disks with data rates not exceeding 1.2 megabytes per second. The UDA50 can handle disk data
rates up to almost 3 megabytes per second.
DSA
DISK
HOST CPU
0
UNIBUS
~>
UDA50
DSA
DISK
-
DSA
DISK
""'--
IL
CPU
CABINET
T
SHIELDED
CABLES
1
DISK
CABINET
The UDA50:
•
•
•
•
•
•
Supports high speed disk technology
Provides powerful error correcting systems for high density recording
Provides multiple level, performance optimizations for both single and multiple drive subsystems.
Provides superior availability features
Supports Winchester fixed-media disks as well as removable-media disks of varying capacities and
transfer rates
.
Unburdens the host system of the overhead associated with errQr handling and I/O throughput
optimization
19
UDA50 OPERATION AND HARDWARE
UDA50 operations are controlled by a high-speed, 16-bit processor which simultaneously executes host
interface and drive interface programs.
The Host Interface Program
•
Reads MSCP packets from host system memory
•
Decodes MSCP packets
•
Transfers data to and from host system memory
•
Calculates the EDC and checks for EDC errors
•
Performs seek ordering
•
Manages the host interface
Logic to timeshare the processor for
simultaneous execution of host and
drive interface programs.
2048-word (l6-bit) memory contains
constants used in error corrections and
logical-to-physical address
Custom lSI logic to interface to UNIBUS
requires only two UNIBUS I/O page
addresses.
4096 words (48 bits) of control memory
with parity protection. Stores both the
host and drive interface programs and
the UDA50 microdiagnostics.
20
The Drive Interface Program:
•
•
•
•
•
•
Checks for ECC errors and performs error recovery
Generates and checks the autocorrelated sync character
Performs overlapped seeks and rotational optimization
Performs seek error recovery
Transfers data to and from the disk drives
Manages the drive interface
The physical configuration of the UDA50 consists of two HEX-size modules that interface to Small
Peripheral Controller (SPC) slots in a PDP-II or VAX UNIBUS.
Logic to implement the SOl protocol
and radial disk interconnect. The
encode/decode logic converts data
between NRZ and SOl code.
Custom LSI logic to implement the
170-bit error correction code.
Custom LSI logic converts data
between serial disk data and parallel
data for UOA50 processing and
transfer to host.
4096-word RAM (16-bit) with byte
parity. Used for temporary storage of
data, commands, and drive
characteristics.
Modularized Power Converter
21
NOTES
THE RA60: THE REMOVABLE MEDIA SOLUTION
The RA60 with 205 megabytes of user capacity is the industry's highest capacity removable-media disk in
a 10.4-inch high form factor. Up to three drives can be packaged in a waist-high cabinet.
Purchase Price discountable.
Note the low quantity one purchase prices and service charges. All products are Type I
205 Mb Per Drive
615 Mb Per Cabinet
820 Mb Per Subsystem
$22,000 Subsystem with $110
Monthly Maintenance Charge
42 ms Average Seek Time
2.0 Mb/Second Burst Data Rate
UDA50 Performance Optimization,
Data Integrity, and High Availability
Features.
$15,000 Drive Price with $80 Monthly
Maintenance Charge
Lifetime Cost of Ownership - Lifetime cost of ownership represents the total cost of purchasing, installing
and maintaining a product. Since the cumulative cost of service sometimes exceeds the initial purchase price,
the only sensible way to compare price is on a lifetime cost-of-ownership basis. The following lifetime
cost-of-ownership figures were calculated on an after-tax, discounted cash flow basis over a five year period,
for a company using double declining balance depreciation, with a 50% tax rate and paying 10% for the cost of
capital (discount rate). Before making a decision, calculate the full cost of ownership for your company!
LIFE CYCLE COST OF OWNERSHIP
Subsystem cost-of-ownership
Drive (with pack) cost-of-ownership
$ 15,800 or $ 77 per megabyte
$1 1, 100 or $54 per megabyte
23
FEATURES SUMMARY
UDA50/RA60 SUBSYSTEM
RA60 DISK DRIVE
• Data Integrity Features
• Formatted User Capacity
•
•
•
•
•
•
•
•
•
•
•
•
• 205 MB per dri ve
• 615 MB per cabinet
• 820 MB per controller
170 bit ECC
Error detecting code (EDC)
Address verification system
Improved disk mapping
Automatic sector retirement
Data compare commands
Access command
S~ek error recovery
Error reporting
Multi-block transfer control
Parity checking
Autocorrelated synchronization
• Performance
• 7 ms single track seek
• 42 ms average seek
• 50 ms average access
• 2.0 MB/second data rate
• Space Efficiency
• Throughput Features
•
•
•
•
•
•
•
•
• III MB/square foot
Command queue
Seek ordering
Overlapped seeks
Rotational optimization
Express queue
Speed matching buffer
Direct revectoring system
DMA transfers
• Dual Access
• Standard feature
• Other Drive Features
•
•
•
•
•
•
•
• Availability Features
•
•
•
•
•
•
•
•
•
•
Radial interconnect
On-board microdiagnostics
Console fault display
Off-line repair
Remote diagnosis support
Power-up verification
Electrical bus isolation
Environmental sensors
No head al ignment
High MTBF/low MTTR
Advanced read/write system
Embedded servo technology
Dual microprocessors
Misalignment compensation
Optimized spindle motor
LSI and modular design
Universal power supply
• Recording Technology
• 779 tracks per inch
• 9,668 bits per inch
• Drive Dimensions
• Height- 10.4" (26.7 cm)
• Width - 18.9" (48.0 cm)
• Depth - 33.5" (71.4 cm)
24
RA60 DISK DRIVE FEATURES
Advanced Read/Write System
The read/write system uses a unique encoding/decoding scheme, named 2/3 rate tree code, to store data on
the disk. The code achieves an optimum balance between maximizing data compaction (three flux changes
express four bits) and minimizing error propagation (transition detection window equals .67 bit length).
BENEFIT
Provides a third more capacity by converting 7251 magnetic flux
changes per inch (FeI) into 9668 bits per inch (BPI) without
compromising data reliability.
Embedded Servo Positioning System
A unique servo code embedded between sectors is used for seeking and track following. Each read/write
head self-positions on the track center line before transferring data.
BENEFIT
Reliable pack interchange at 779 tracks-per-inch (TPI) eliminates
the need for costly head alignments; results in higher capacity by
eliminating the need to allocate a disk surface for servo information.
Optimized Cylinder Configuration
A logical cylinder consists of a group of four adjacent tracks on the same surface.
BENEFIT
Horizontal arrangement of cylinders minimizes head switch latency in drives that utilize only embedded servo systems by canceling the effect of any vertical misalignment of tracks or heads.
Dual Microprocessor Architecture
One microprocessor controls major drive functions while a second microprocessor communicates with the
controller.
BENEFIT
Enhances performance by allowing simultaneous tasks to occur.
Universal Power Supply
The RA60 operates with any combination of 50/60 Hz and 120Y /240Y input power. Reversing two pI ugs
on the transformer converts frequency, and a switch, also on the transformer, converts voltage.
BENEFIT
The ease of power conversion minimizes inventory for system
OEM customers and provides flexibility for multi-national corporations.
Automatic Misalignment Compensation System
The drive automatically senses and compensates for radial misalignment by phase-locking position and
spindle speed to the microprocessor. For axial misalignment, it uses a grey code compensation system.
BENEFIT
Insures data integrity and reliable pack interchange. Eliminates the
need for periodic head alignment.
25
Optimized Spindle Motor
A brushless DC spindle motor is used to drive the rotating pack. An impeller, mounted on the motor, is the
primary air flow mechanism in the cooling system.
BENEFIT
Decreases power consumption, heat dissipation and acoustic
noise. Eliminates the conventional motor-to-spindle pulley belt
and blower assembly.
Extensive LSI and Modular Design
The drive uses gate array and hybrid LSI components extensively. The logic is functionally partitioned on
the modules. Every component is part of a field replaceable unit.
BENEFIT
Improves mean time between failures (MTBF) by reducing parts
count and improves MTTR through design modularity.
26
THE RA80: ENTRY LEVEL DSA DISK
Paired with the RL02, the RA80 disk provides a complete storage solution that includes 121 megabytes of
high performance Winchester disk capacity and a 10 megabyte removable media companion disk for software
distribution, private files, data interchange and data back-up.
Purchase Price discountable.
Note the low quantity one purchase prices and service changes. All products are Type I
10 Mb of User Capacity
500 KB/Second Burst Data Rate
55 ms Average Seek Time
$3,000 Drive with $63 Monthly
Maintenance Charge
121 Mb of User Capacity
1.2 Mb/Second Burst Data Rate
25 ms Average Seek Time
$14,000 Drive Price with $81 Monthly
Maintenance Charge
Lifetime Cost of Ownership - Lifetime cost of ownership represents the total lifetime cost of purchasing,
installing and maintaining a product. Since the cumulative cost of service sometimes exceeds the initial
purchase price, the only sensible way to compare price is on a lifetime cost-of-ownership basis. The following
lifetime cost-of-ownership figures were calculated on an after-tax, discounted cash flow basis over a five year
period, for a company using double declining balance depreciation, with a 50% tax rate and paying 10% for the
cost of capital (discount rate). Before making a decision, calculate the full cost of ownership for yourcompany!
LIFE CYCLE COST OF OWNERSHIP
RL02
RA80
• Subsystem
• Add-on
-
• Subsystem
• Add-on
$15,100
$10,400
27
-
$5,900
$3,300
FEATURES SUMMARY
UDASO/RA80 SUBSYSTEM
RA80 DISK DRIVE
• Data Integrity Features
• Formatted User Capacity
•
•
•
•
•
•
•
•
•
•
•
•
• 121 MB per drive
• 363 MB per cabinet
• 484 MB per controller
170 bit ECC
Error detecting code (EDC)
Address verification system
Improved disk mapping
Automatic sector retirement
Data compare commands
Access command
Seek error recovery
Error reporting
Multi-block transfer control
Parity checking
Autocorrelated synchronization
• High Performance
•
•
•
•
• Space Efficiency
• Throughput Features
•
•
•
•
•
•
•
•
• 83 MB/ square foot
Command queue
Seek ordering
Overlapped seeks
Rotational optimization
Express queue
Speed matching buffer
Direct revectoring system
DMA transfers
• Dual Access
• Standard feature
• Other Drive Features
•
•
•
•
• Availability Features
•
•
•
•
•
•
•
•
•
•
•
6 ms single track seek
25 ms average seek
33 ms average access
1.2 MB/second data rate
Winchester technology
Radial interconnect
On-board diagnostics
Console fault display
Off-l ine repair
Remote diagnosis support
Power-up verification
Electrical bus isolation
Environmental sensors
High MTBF/low MTTR
No scheduled PM
Innovative head-disk assembly
Recirculating air filtration
Dual read/write heads
Modular design
• Recording Technology
• 478 tracks per inch
• 6,339 bits per inch
• Drive Dimension
• Height - 10.4" (26.7 cm)
• Width - 18.9" (48.0 cm)
• Depth - 26.5" (71.4 cm)
28
RA80 DISK DRIVE FEATURES
Winchester Technology
The enclosed head disk assembly protects the recording environment from external contaminants.
Lightweight head suspension allows heads to fly closer to the surface.
BENEFIT
Improved data reliability by virtually eliminating head-disk interference. Increases recording density for higher capacity and lower
cost per megabyte.
Innovative Head-Disk Assembly (HDA)
The HDA is formed from two symmetrical aluminum castings with top and bottom spindle bearings.
BENEFIT
Stiff platform with double bearings minimizes axial runout and
off-track errors.
Recirculating Air Filtration System
An absolute filter is designed into the spindle assembly. The disk platters provide a pumping action which
exhausts air from the space between the disk platters causing air flow through the absolute filter.
BENEFIT
The recirculating air filtration system protects data. If an oxide
particle becomes free within the HDA, it will be trapped in the
filter before damage occurs.
Computer Designed Positioner
The low mass rotary positioner includes an innovative moving magnet design.
BENEFIT
High seek performance, compact size and low power consumption.
Dual Read/Write Heads
Two read/write heads address each data surface. A logical cylinder consists of two physical cylinders.
BENEFIT
Two heads per surface provide twice the data at every actuator
position. This reduces seek activity and shortens average seek
distances for improved performance.
Environmental Sensors
Thermal and speed sensors monitor air temperature and spin-up acceleration.
BENEFIT
Protects data from degradation caused by extreme heat or line voltage variations.
Modular Design
The electronics are functionally partitioned on separate modules. Every component is part of a field
replaceable assembly.
BENEFIT
Improves system uptime by reducing mean time to repair (MTTR).
29
NOTES
THE RA81: THE LOWEST COST PER MEGABYTE SOLUTION
The RA8l with 456 megabytes of user capacity is the industry's highest capacity Winchester fixed-media
disk in a 1O.4-inch high form factor. The triple drive RA8l option stores almost l.4-billion bytes in about five
square feet.
Purchase Price discountable.
Note the low quantity one purchase prices and service changes. All products are Type I
$26,000 Single Drive Subsystem with
$120 Monthly Maintenance Charge
$19,000 Drive Price with $90 Monthly
Maintenance Charge
28 ms Average Seek Time
36 ms Average Access Time
2.2 Mb/Second Burst Data Rate
UDA50 performance Optimization,
Data Integrity, and High Availability
Features.
$55,000 Triple Drive Subsystem with
$300 Monthly Maintenance Charge
$50,000 Triple Drive Add-On with
$270 Monthly Maintenance Charge
Lifetime Cost of Ownership - Lifetime cost of ownership represents the total lifetime cost of purchasing,
installing and maintaining a product. Since the cumulative cost of service sometimes exceeds the initial
purchase price, the only sensible way to compare price is on a lifetime cost-of-ownership basis. The following
lifetime cost-of-ownership figures were calculated on an after-tax, discounted cash flow basis over a five year
period, for a company using double declining balance depreciation, with a 50% tax rate and paying 10% for the
cost of capital (discount rate). Before making a decision, calculate the full cost-of-ownership for your
company!
LIFE CYCLE COST OF OWNERSHIP
Single Drive Subsystem Single Drive Add-on
-
$18,400 or $40 per megabyte
$13,700 or $30 per megabyte
Triple Drive Subsystem Triple Drive Add-on
-
$39,600 or $29 per megabyte
$36,000 or $26 per megabyte
31
FEATURES SUMMARY
UDA50/RA81 SUBSYSTEM
RA81 DISK DRIVE
• Data Integrity Features
• Formatted User Capacity
•
•
•
•
•
•
•
•
•
•
•
• 456 MB per dri ve
• 1368 MB per cabinet
• 1824 MB per controller
170 bit ECC
Error detecting code (EDC)
Address verification system
Improved disk mapping
Automatic sector retirement
Data compare commands
Access command
Seek error recovery
Multi-block transfer control
Parity checking
Autocorrelated synchronization
• High Performance
• 6 ms single track seek
• 28 ms average seek
• 36 ms average access
• 2.2 MB/second data rate
• Space Efficiency
• Throughput Features
• 253MB / sq uare foot
•
•
•
•
•
•
•
•
Command queue
Seek ordering
Overlapped seeks
Rotational optimization
Express queue
Speed matching buffer
Direct revectoring system
DMA transfers
• Dual Access
• Standard feature
• Other Drive Features
•
•
•
•
•
•
• Availability Features
•
•
•
•
•
•
•
•
•
•
•
Winchester technology
Radial interconnect
On-board diagnostics
Console fault display
Off-line repair
Remote diagnosis support
Power-up verification
Electrical bus isolation
Environmental sensors
High MTBF/low MTTR
No scheduled PM
Advanced read/write system
Dual positioning system
Innovative head-disk assembly
Recirculating air filtration
Dual read/write heads
Modular design
• Recording Technology
• 960 tracks per inch
• 11,400 bits per inch
• Drive Dimensions
• Height - 10.4" (26.7 cm)
• Width - 18.9" (48.0 cm)
• Depth - 26.5" (71.4 cm)
32
RA81 DISK DRIVE FEATURES
Advanced Read-Write System
The read/write system uses a unique encoding/decoding scheme, named 2/3 rate tree code, to store data on
the disk. The code achieves an optimum balance between maximizing data compaction (three flux changes
express four bits), and minimizing error propagation (transition detection window equals .67 bit length).
BENEFIT
Provides a third more capacity by converting 8,550 magnetic flux
changes per inch (FeI) into 11,400 bits per inch (BPI) without
compromising data reliability.
Dual Positioning System
A high bandwidth servo system using a dedicated disk surface is complemented by an inter-sector
embedded servo code for fine positioning.
BENEFIT
Provides for high performance seeking and high precision positioning at 960 tracks per inch (TPI).
Winchester Technology
The enclosed head disk assembly protects the recording environment from external contaminants.
Lightweight head suspension allows heads to fly close to the surface.
BENEFIT
Improves data reliability by virtually eliminating head-disk interference and increases recording density for higher capacity and
lower cost per megabyte.
Innovative Head-Disk-Assembly (HDA)
The HDA is formed from two symmetrical aluminum castings with top and bottom spindle bearings.
BENEFIT
Stiff platform with double bearings to minimize axial runout and
off-track errors.
Computer Designed Positioner
The low mass, rotary positioner includes an innovative moving magnet design.
BENEFIT
High seek performance, compact size and low power consumption.
Dual Read/Write Heads
Two read/write heads address each data surface. Each logical cylinder consists oftwo physical cylinders.
BENEFIT
Two heads per surface provide twice the data at every actuator
position. This reduces seek activity and shortens average seek
distance for improved performance.
Environmental Sensors
Thermal and speed sensors monitor air temperature and spin-up acceleration.
BENEFIT
Protects data from degradation caused by extreme heat or line
voltage variations.
33
Modular Design
The electronics are functionally partitioned on separate modules. Every component is part of a field
replaceable unit.
BENEFIT
Improves system uptime by reducing mean time to repair (MTTR).
Dual Microprocessor Architecture
One microprocessor communicates with the UDA50 and controls major drive functions except real time
operations (such as the servo system) which are controlled by the second microprocessor.
BENEFIT
Enhances performance by allowing simultaneous tasks to occur.
Recirculating Air Filtration System
An absolute filter is designed into the spindle assembly. The disk platters provide a pumping action which
exhausts air from the space between the disk platters causing air flow through the absolute filter.
BENEFIT
The recirculating air filtration system protects data. If an oxide
particle becomes free within the HDA, it will be trapped in the
filter before damage occurs.
34
SPECIFICATIONS SUMMARY
UDASO Specifications
Characteristics
Specification
Physical Components
UDA Module # 1
UDA Module #2
50-pin flat cable assembly
40-pin flat cable assembly
UDA50 to I/O bulkhead cable
I/O bulkhead assembly
Power Consumption
75 Watts
Heat Dissipation
Approximately 256 Btu/hour
Electrical Voltage
and Current Requirements
11 amps at + 5 volts
60 millamps at + 15 volts
2 amps at -15 volts
Operating Temperature
Range
10°C to 40°C (50°F to 104°F)
with a temperature gradient of 20°C/ hour (36°F/hour)
Operating Relati ve
Humidity Range
10% to 90% with a wet bulb
temperature of 28°C (82°F), and a
minimum dew point of 2°C (36°F)
Operating Altitude
Range
Sea level to 2438 meters (8000 ft)
Maximum allowable operating
temperature derated by 1. 8°C/ 1000
meters (1 °F/ 1000 feet) for operation
above sea level
Mounting Restrictions
Mounts in two hex-height UNIBUS SPC
slots in the CUP box or the
following UNIBUS expander boxes:
BAI1-A
BAII-K
BA11-L
Controller-to-Drive Cable
Standard length: 12 feet (3.7) meters
Optional lengths: 25, 50, 80 feet
(7. 6, 15.2, 24.4 meters)
35
RA80, RA81, RA60 Specifications Summary (Cont)
RA80
RA81
RA60
Physical Specifications:
Sectors per track
Tracks per surface
Recording surfaces
Tracks per disk
32
1116
7
7812
52
2496
7
17612
43
1600
6
9600
User Data Capacity:
Bytes per sector
Sectors per track
Tracks per logical cylinder
Logical cylinders per drive
Megabytes per disk
Drives per cabinet
Megabytes per cabinet
Drives per controller
Megabytes per controller
512
31
14
546
121
3
363
4
484
512
51
14
1248
456
3
1368
4
1924
512
42
4
2382
205
3
615
4
820
Reserved Space:
Replacement sectors/track
Replacement sectors/disk
Tracks for bad block table
Tracks for diagnostic use
1
7700
104
56
1
17528
112
28
1
9552
48
24
478
6339
960
11400
779
9668
1.2 MB/Sec
2.2 MB/Sec
2.0 MB/Sec
6 ms
25 ms
50 ms
8.3 ms
33.3 ms
Oms
6 ms
28 ms
52 ms
8.3 ms
36 ms
4 ms
7 ms
42 ms
70 ms
8.3 ms
50 ms
7 ms
Data Organization
Recording Density
Tracks per inch (TPI)
Bits per inch (BPI)
Performance *
Peak transfer rate
Seek times:
Track-to-track
Average
Maximum
Rotational latency
A verage access time
Typical head switch time
* Note: In most observed seek performance will be significantly better than the (above)
specified seek times for the drives due to the UDA50's performance optimizations. In
single drive systems with a heavy I/O load, seek ordering will reduce the effective
average seek time by up to 35%. In multiple drive systems, overlapped seeking and
rotational optimization can provide additional significant reductions in effective seek
performance. The actual performance that the user will see is dependent on the I/O
workload, the number of drives in the subsystem and the distribution of files on the
drives. In general, the increase in I/O throughput in DSA subsystems caused by the
performance optimization features is positively correlated with the number of drives in
the subsystems - the more drives, the better the performance.
36
RA80, RA81, RA60 Specifications Summary (Cont)
Operation
Start time
Stop time
Rotational speed
RA80
RA81
RA60
50 seconds
20 seconds
3600 RPM
50 seconds
20 seconds
3600 RPM
35 seconds
35 seconds
3600 RPM
31.0 A
7.1 A
36.6 A
7.8 A
10.4 A
8.6 A
5.2 A
4.3 A
Power
120V, 60Hz, single phase
Turn-on current
Running current
240V, 50Hz, single phase
Turn-on current
Running current
Plug types
120V
240V
17.0A
3.5 A
18.0A
3.5 A
NEMA 5-15P
NEMA 6-15P
NEMA 5-15P
NEMA 6-15P
NEMA 5-15P
NEMA 6-15P
Heat Dissipation
BTU s per hour
Watts
2200
650
2200
650
2400
700
4
7
6
Embedded
2
4
7
1
2
60 dB(A)
58 dB(A)
60 dB(A)
58 dB(A)
65 dB(A)
65 dB(A)
10° to '40° C
(50° to 104° F)
10° to 38° C
(50° to 101° F)
10° to 40° C
(50° to 104° F)
10° to 40° C
(50° to 104° F)
16° to 40° C
(60° to 104° F)
16° to 40° C
(60° to 104° F)
Altitude (maximum)
2438m (8000 ft)
2438m (8000 ft)
2438m (8000 ft)
Relative humidity
10% to 85% (no
condensation)
Maximum wet
bulb temperature
of 28°C (82°F)
and minimum dew
point of 2°C
(36°F)
10% to 85% (no
condensation)
Maximum wet
bulb temperature
of 28°C (82oF)
and minimum dew
point of 2°C
(36°F)
8% to 80% (no
condensation)
Maximum wet
bulb temperature
of 26°C (79°F)
and minimum dew
point of 2°C
(36°F)
Heads and Disks
Number of platters
Data surfaces
Servo surfaces
Heads per data surface
Acoustics
60 Hz drive
50 Hz drive
Operational Environment
Temperature range at sea level
60 Hz drives
50 Hz drives
1
37
3
1
RA80, RA81, RA60 Specifications Summary (Cont)
Mechanical
Drive
Height
Width
Depth
Weight
Drive in Cabinet
Height
Width
Depth
Weight
RA80
RA81
RA60
10.4" (26.4 em)
17.5" (44.5 em)
26.5" (67.3 em)
148 lbs (67 kg)
10.4" (26.4 em)
17.5" (44.5 em)
26.5" (67.3 em)
148 lbs (67 kg)
10.4" (26.4 em)
17.5" (44.5 em)
33.5" (85.1 em)
165 lbs (75 kg)
41.8" (106.3 em)
21. 3" (54.2 em)
36" (14.2 em)
363 lbs (185 kg)
41.8" (106.3 em)
21.3" (54.2 em)
36" (14.2 em)
363 lbs (185 kg)
41.8" (106.3 em)
21.3" (54.2 em)
36" (14.2 em)
370 lbs (168 kg)
Yes
Yes
Yes
Compliant
Yes
Yes
Yes
Compliant
Yes
Yes
Yes
Compliant
Regulatory Agencies
UL
VDE
CSA
FCC
38
DIGITAL EQUIPMENT CORPORATION, COLORADO SPRINGS, COLORADO 80963
EA-24042-18 Printed in USA Copyright
©
1982 Digital Equipment Corporation All Rights Reserved.
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