Shingled Magnetic Recording Mitch Rose Director Technical Customer Management Seagate Technology Contents: SMR types Zone Block Devices Open Source Reference Host Aware SMR Measured Data SMR role in HDD offerings 2 Drivers of Data Growth INTERNET OF THINGS MOBILITY Smartphones and Tablets Nest, Apple Watch, Fitbit, Google Glass, Wearable Technology SURVEILLANCE AND SECURITY Smart City, Shopping Malls BIG DATA ANALYTICS Waze, Splunk, Hadoop HD AND MEDIA-RICH VIDEO IPhone 4K Video, Virtual gaming BIG DATA TO REACH $125B IN 2015 3• Source: IDC, December 2014 3 Data Explosion vs. Areal Density Growth SMR Data Growth IT Budget shortfall 2011 4Company estimates 2012 Areal Density Growth 2013 2014 2015 2015 2016 2017 4 Storage Trends Driving SMR • High capacity – Fast sequential write and read requirements – Lower random performance – command rate, latency – SMR disk, tape • High performance – Fast random write requirements – Disk (conventional, high spin speed), Flash, NV storage-class memories 5 SMR Applications Application Capacity Optimized (Cost per capacity priority) 1. Zone Aware storage stack 2. Predominately sequential writing 3. Host Aware SMR Fill-once applications Tolerant of higher command latency variance Drive Managed SMR Specifically due to random writes Performance Optimized (Cost per IOPs priority) 1. Customer doesn’t own stack 2. Cannot tolerate lower performance, specifically higher command latency variance 6• Best Fit *stack: may include hardware, software, & storage architecture defining key elements of an Application’s QoS (Quality of Service) Conventional Drives (CMR) 6 Conventional versus SMR Writing Reader Writer Conventional Writing TrackNN Track Track TrackN+1 N+1 Track TrackN+2 N+2 Track TrackN+3 N+3 Writer Reader Shingled Writing: 5-track band TrackNN Track TrackN+1 N+1 Track TrackN+2 N+2 Track TrackN+3 N+3 Track TrackN+4 N+4 Track 7 Copyright © Seagate Technology, Dec 2014 SMR - Improving Write Performance Write-around for sequential writes Band 0 Data from host Band 1 Disk Cache • Write-back disk* cache • Multiple commands cleaned during a band update Band 2 … Band max * HDD conventional area for caching data. 8 Copyright © Seagate Technology, Dec 2014 ZBC/ZAC Standards SMR Drive Types SMR Category Description Drive Managed (DM) Supported Zone Types Device Type Conv. Seq’l Wr Required Seq’l Wr Preferred • Backward Compatible • Drive autonomously hides all SMR issues • Performance profile changes 00h n/a n/a n/a Host Managed (HM) • Not backward compatible • New Device Type • Error conditions for some reads & writes • Zoned block device commands 14h Optional Required Not Allowed Host Aware (HA) • Backward Compatible • Superset of Drive Managed and Host Managed • Zoned block device command support 00h Optional Not Allowed Required 9ZBC: Zoned Block Commands (T10 for SAS); ZAC: Zoned-block ATA Commands (T13 for SATA) © Seagate Technology 2015 9 Advantages of Host Aware • Host Aware advantages Host Aware – Every Host Aware drive uses underlying Drive Managed architecture – Fault tolerant accepting writes not at the write pointer – Random write capable inside advisory limits Drive Managed features Host Managed features - A superset of features - Host Aware Extensions • Drive Managed SMR (foundation) • 10 Seagate Technology 2015 Host Aware is interchangeable with Host Managed – Host Aware uses the same standard as Host Managed – If a Host makes the needed changes, HM and HA will offer competitive performance 10 SMR Bands and Zones • Conceptually, a zone is one or more bands Bands Zones Groups of tracks Groups of LBAs Bx-1 LBA max • – Not visible to the host WP Zone n-1 Bx-2 … … B2 Zone 2 B1 Zone 1 B0 Zone 0 Band: a physical grouping of tracks • Zone: a range of LBAs – Zone configuration is exposed through new REPORT ZONES command – Write Pointer and Conventional Zone Types WP WP • Zone use & Write Pointers (WP) – Each non-conventional zone has a write pointer – Write pointers track location for next sequential write LBA 0 physical • 11 • Writes that start at the write pointer advance the write pointer logical ZBC: Zoned Block Commands (T10 for SAS); ZAC: Zoned-block ATA Commands (T13 for SATA) 11 Host Aware Goals • Enable SMR at parity performance - Advisory parameters express intended use model - Minimal use of media cache - Minimal effect to command latency variance • In a nutshell Empty Zone Reset Open • LBA grouped in zones exposing SMR bands • Sequential writes go straight to main store • • Reset Write Pointer before re-write Writes at write pointer do not require read-modify-write Full • Random writes go to media cache • Conventional zones for host metadata • Lamarr HA: 16 GiB out of 8 TB • • 12 Seagate Technology 2015 0.2% of capacity 12 Host Aware SMR Performance – A micro-benchmark with workloads that conforms to the zoned block device intended use model – Demonstrates that Host Aware SMR has parity performance as CMR when used as intended – Seagate has modified Iometer to perform zone-aware workloads 2000 1000 0 250 • Available from Seagate Technical Support Seagate Technology 2015 200 150 100 50 0 QD 1 to 128 Transfer Size • 13 CMR 7200rpm 6TB HA SMR 5900rpm 8TB CMR 5900rpm 4TB 3000 WCE Sequential Write MB/s • Zoned Iometer 4000 WCE Random Write IOPS • Meet or beat conventional drive performance 4k 8k 16k 32k 64k Seagate Confidential 128k 256k 512k 13 1MiB SATA Host Aware In Linux User Space Software libzbc / ZAC libzbc – Adds support for ZAC commands in user space providing the option of sg_utils Operation System Kernel Space EXT4 SMR Friendly File System • Currently working on single drive HDD readiness (v0.5) • http://www.github.com/seagate/SMR_FS-EXT4 File System / ZAC Device mapper / LVM Block Layer (IO scheduler) SAS SAT SCSI SATA pass through Software RAID – Device mapper solutions being investigated by HDD vendors for compatibility with legacy non-ZAC compliant file systems SCSI – SCSI / sd_zbc for ZBC commands SCSI SAS HBA/RAID Expander application level management SAT SAT – Linux patches backward to 2.6 ZAC libata libata – ZAC command support (starting 3.18 kernel) AHCI SATA HA SMR 14 14 HA SMR – Seagate view of Timeline Q3 ’15 Seagate HA SMR Drives ZBC / ZAC Standards File System EXT4 SMRFFS 15 Q4 ’15 Design in partners engaged Q1 ’16 HDD qualification readiness ZAC projected T13 approved ZBC T10 approved V.0.5 FS Changes Volume production V.0.6 User Utils HDD + SMRFFS integration V.0.7 projected milestone LVM RAID development 15 Who else is making “friendly” changes for SMR? Open Source • Linux File Systems: EXT4, XFS, btrfs, & more • Software Defined Storage & Object SW Closed Source / Proprietary • Efforts underway for FS, Software defined storage, Hardware partners, & cloud providers • Nothing to announce, today 16 16 Resources t10.org ZBC: SCSI Zoned Block Commands letter ballot review, now t13.org ZAC: ATA Zoned ATA Commands github.com/hgst/libzbc Linux user space libraries for application access to zone block devices github.com/Seagate/SMR_FS-EXT4 Improvements to ext4 for zoned block devices github.com/westerndigitalcorporation/smr-simulator Device mapper target that emulates a zoned block device 17 Copyright©2015 Huawei Technologies Co., Ltd. All Rights Reserved. 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