Your SlideShare is downloading. ×
IBM System Storage DS8000 with SSDs An In-Depth Look at SSD Performance in the DS8000
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

IBM System Storage DS8000 with SSDs An In-Depth Look at SSD Performance in the DS8000

1,667

Published on

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,667
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
20
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. ® ®IBM System Storage DS8000 with SSDsAn In-Depth Look at SSD Performance in the DS8000Performance White PaperApril 27, 2009Lee LaFreseLeslie SuttonDavid WhitworthStorage Systems PerformanceSystems & Technology GroupInternational Business Machines Corporation
  • 2. Notices and DisclaimerCopyright © 2009 by International Business Machines Corporation.No part of this document may be reproduced or transmitted in any form without written permission fromIBM Corporation.Product data has been reviewed for accuracy as of the date of initial publication. Product data is subjectto change without notice. This information may include technical inaccuracies or typographical errors.IBM may make improvements and/or changes in the product(s) and/or programs(s) at any time withoutnotice. References in this document to IBM products, programs, or services does not imply that IBMintends to make such products, programs or services available in all countries in which IBM operates ordoes business.THE INFORMATION PROVIDED IN THIS DOCUMENT IS DISTRIBUTED "AS IS"WITHOUT ANY WARRANTY, EITHER EXPRESS OR IMPLIED. IBM EXPRESSLYDISCLAIMS ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR APARTICULAR PURPOSE OR NON-INFRINGEMENT. IBM shall have no responsibility to updatethis information. IBM products are warranted according to the terms and conditions of the agreements(e.g., IBM Customer Agreement, Statement of Limited Warranty, International Program LicenseAgreement, etc.) under which they are provided. IBM is not responsible for the performance orinteroperability of any non-IBM products discussed herein.The performance data contained herein was obtained in a controlled, isolated environment. Actualresults that may be obtained in other operating environments may vary significantly. While IBM hasreviewed each item for accuracy in a specific situation, there is no guarantee that the same or similarresults will be obtained elsewhere.Statements regarding IBM’s future direction and intent are subject to change or withdrawal withoutnotice, and represent goals and objectives only.The provision of the information contained herein is not intended to, and does not; grant any right orlicense under any IBM patents or copyrights. Inquiries regarding patent or copyright licenses should bemade, in writing, to:IBM Director of LicensingIBM CorporationNorth Castle DriveArmonk, NY 10504-1785U.S.A.IBM, System Storage, DS8000, FICON, FlashCopy, and z/OS are trademarks of International BusinessMachines Corporation in the United States, other countries, or both.Other company, product or service names may be trademarks or service marks of others. IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 1 of 14
  • 3. IntroductionIn February 2009, IBM announced the IBM System Storage DS8000 Turbo series with Solid StateDrives (SSDs).[1,2]SSDs have no moving parts so they perform at electronic speeds without the mechanical delaysassociated with traditional spinning Hard Disk Drives (HDDs). Because SSDs enable dramaticallyhigher throughput and lower response times for random I/O than HDDs, they provide the potential tosignificantly lower operational costs in the data center despite substantially higher current acquisitioncost per GB. To realize these benefits, it is key to specifically target usage to applications that requirehigh IOPS/GB and/or low response times. Previously, customers were forced to buy large quantities of15K RPM HDDs for these applications and use only a small portion of the capacity of each HDD(known as short stroking) to meet their performance requirements. This practice can be costly as itreduces capacity utilization. Now a large number of HDDs may be replaced with a small number ofSSDs, fully utilizing the capacity of each SSD and realizing improved system performance while alsosaving on space, power, and cooling.SSD Performance Best Practices 1. Place hot data on SSDs, warm data on 15K RPM HDDs, and cold data on 7200 RPM SATA HDDs (see section on “Selecting Data to Place on SSDs” below for more details). 2. Use SSDs for applications that require low response times and are cache unfriendly. 3. SSDs are many times faster than HDDs at random I/O, but only slightly faster than HDDs at sequential I/O. Data that is accessed randomly should be placed on SSDs and data that is accessed sequentially should be placed on HDDs. 4. Use SSDs for applications that traditionally short stroke large numbers of 15K RPM HDDs. 5. Consider using a smaller storage cache when using SSDs than you might when using HDDs. Disk Magic may be used to predict whether the combination of SSDs and a small storage cache will meet the response time requirement. For hybrid DS8000s containing both SSDs and HDDs it is advisable to use the same size storage cache as you would for a configuration of all HDDs so that read hit ratios on the volumes placed on the HDDs are not reduced. 6. There is no additional benefit to using SSDs with remote copy services. In general, if SSDs are used for remote copy source volumes they should also be used for the remote copy target volumes. If not, then the secondary HDD based targets may become the bottleneck in the system. This is especially problematic for synchronous replication (Metro Mirror) as delays will be pushed back to applications. For asynchronous replication (Global Mirror) you may see an increase in recovery point objective (RPO) if the throughput to the primary far exceeds the secondary capability. This may or may not be acceptable depending on service level agreements. The important thing here is to do the appropriate capacity planning before placing SSDs into a remote copy environment. 7. SSDs may be used with FlashCopy either for source or target volumes. If SSDs are used for source volumes while HDDs are used for the secondary, it is a good idea to do the FlashCopy with background copy and during a period when the write rate to source volumes does not IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 2 of 14
  • 4. exceed the capability of the targets. Additionally, although SSDs would likely perform well as a Space Efficient FlashCopy (SEFLC) target repository, it does not fit with the basic premise of the technology. SEFLC is intended for cost reduction by not fully provisioning the FlashCopy target space. Since SSDs are costly it is likely that fully provisioned HDD space would be less expensive and perform at least as well. 8. Use High Performance FICON for System z (zHPF) with SSDs for higher throughput and additional reduction in the total response time.Selecting Data to Place on SSDsThe DS8000 now supports 3 performance tiers of storage:• Tier 0: SSDs. Highest performance and cost/GB• Tier1: 15K RPM HDDs. High performance and lower cost/GB.• Tier2: 7200 RPM HDDs. Lowest performance and cost/GB.To maximize the benefit of SSDs it is important to only place data which requires a high IOPS/GB andlow response time on them. This data is referred to as “hot” data. Data that requires a low IOPS/GB isreferred to as “cold” data. Once hot data is moved to SSD, the remaining data may be cold enough toallow moving a large portion of it to high capacity 7200 RPM HDDs and still meet the requiredperformance. Using the right mix of tier 0, 1, and 2 drives will provide optimal performance at theminimum cost, power, cooling and space usage.Determining the temperature of data and moving it to the proper tier can be difficult, so IBM providestools to help with this process.Data placement on Power System serversAIX provides performance tools that can be used to determine if a configuration has hot data that wouldperform better if moved to SSDs.First use the “iostat” command to check the CPU utilzation. iostat breaks down the CPU utilization intousr, sys, idle, and iowait time. If there is a substantial amount of iowait time, then speeding up thestorage could potentially improve application performance.The “iostat –D” command can then be used to get detailed storage performance statistics. For each LUNit shows the percent time active and the throughput as well as details on read and write response timesand queueing delays. Look for LUNs that are 99 to 100% busy and have long response times/queueingdelays.Next, run the “filemon” command to get detailed reports on the hotest AIX logical volumes and files.Filemon’s detailed reports show statistics on read and write response times, I/O sizes, and seekdistances. Look for logical volumes and files that do a lot of very random small block I/O and have longresponse times.Consider moving data with the highest IOPS/GB to SSD first. The AIX migratepv command or theSoftek Data Mobility Services tools can be used to move data while it is online. IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 3 of 14
  • 5. The whitepaper “Driving Business Value on Power Systems with Solid State Drives”3 provides adetailed example of using to iostat and filemon to find hot data and of using Softek Data MobilityServices to move that data to SSDs to improve application performance.Data placement on System z serversThe System z I/O architecture provides a detailed breakdown of time spent executing I/O operations. Ona machine that runs z/OS in zArchitecture Mode with the Extended I/O Measurement Facility, thesetimes are stored into the I/O measurement word whenever an I/O interrupt occurs. Additionally, theseI/O measurements are aggregated into the channel measurement blocks for every device enabled to usethe I/O measurement facility.One of the measurements surfaced to z/OS is the device disconnect time (DISC). Disconnect time is ameasure of the time spent resolving cache misses for read I/O operations. Disconnect time also includesthe time it takes to perform synchronous replication for write I/O operations using, for example, IBM’sMetro Mirror technology on the DS8000. Solid state drives are ideally suited to benefit workloads thatare incurring high numbers of cache misses (for example, random reads) but are not expected tosubstantially reduce the elapsed times for use of synchronous replication technologies.For this reason, the DFSMS instrumentation that captures these components of I/O service time forevery I/O operation by data set has been enhanced to separate the disconnect time spent for readoperations from the disconnect time spent for write operations. (This support is available with DFSMSSSD support APAR OA25559)The SMF 42 subtype 6 record now includes two new fields: • S42DSRDD reports the average read disconnect time for the interval per data set. • S42DSRDT includes the total number of read operations performed to the data set during the interval.The DS8000 also provides the ability to obtain cache statistics for every volume in the storagesubsystem. These measurements include the count of the number of operations from DASD cache to thebackend storage, the number of random operations, the number of sequential reads and sequentialwrites, the time to execute those operations, and the number of bytes transferred. These statistics arereported in the SMF 74 subtype 5 record.New z/OS tooling has been provided to analyze the SMF 42-6 and 74-5 records and produce a series ofreports identifying data sets and volumes that can benefit from residing on SSD. This new tooling isbased on SAS® software and is now available for download from the MVS Tools and Tips web page athttp://www.ibm.com/systems/z/os/zos/downloadsSMF data from an extended time period may be processed to get an overall historical view of I/Oactivity, or much smaller time periods may be specified to focus on peak loads, batch windows, marketopen, and other special conditions of interest.The first report (generated from SMF 42-6 records) analyzes data sets for a high amount of total readdisconnect time which is a symptom of frequent read cache misses. Data set size is also factored in, if IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 4 of 14
  • 6. available. Solid state drives significantly reduce the I/O service time caused by a cache miss, so data setsappearing near the top of this list should be considered first for migration to SSD.The second report (generated from SMF 74-5 records) analyzes DASD cache statistics to identifyvolumes with high I/O rates. A pseudo device load is calculated in order to identify the devices that arecausing the highest load on the backend disks. Volumes with the highest pseudo device loads may beconsidered for full volume migration to SSD.The remaining reports are generated by merging the volume view with the data set view to identify thehottest data sets on the most stressed volumes. Movement of individual data sets from these volumesshould be considered as an alternative to full volume migration when SSD space is limited.More details on z/OS SSD instrumentation and tooling can be found in the article “Stop spinning yourstorage wheels: z/OS Support for solid state drives in the DS8000 storage subsystem” in z/OS HotTopics Newsletter, Issue 20 at http://www.ibm.com/servers/eserver/zseries/zos/bkserv/hot_topics.htmland the FLASHDA User’s Guide at http://publibz.boulder.ibm.com/zoslib/pdf/flashda.pdfSAS and all other SAS Institute Inc. product or service names are registered trademarks or trademarks ofSAS Institute Inc. in the USA and other countries. ® indicates USA registration.Storage Modeling and Analysis ToolsDisk Magic is a performance modeling tool used by IBM which can help you predict the expectedperformance of a DS8000 with a specific configuration running a specific workload. In the short term,the tool has been enhanced to model the performance of SSDs. It will be possible to evaluate placementof specific workloads on SSDs while other workloads remain on HDDs. Future enhancements areplanned to help the user determine which workloads or volumes are best to move from HDDs to SSDs.As with any modeling tool, the quality of the output will depend on the accuracy of the input datadescribing the workload characteristics. Customers should contact their IBM Storage Sales Specialist orIBM Business Partner if they are considering SSDs for their DS8000 and would like to have aperformance modeling study done.Updates to other IBM sales tools such as RMF Magic and Capacity Magic for SSD support are alsoplanned. Taken together, this tool set will enable thorough performance analysis of potential DS8000SSD implementations.Performance ResultsPerformance results in this section compare SSDs vs. HDDs in the DS8000 for a variety of differentworkloads.For random I/O, SSDs provide much higher throughput at a much lower response time than HDDs. TheSSDs supported in the DS8000 are so fast that the Device Adapter (DA) may become the performancebottleneck on some random workloads. For sequential I/O, the DA was already the performancebottleneck with HDDs. Using SSDs for sequential I/O does not provide a substantial increase inperformance. IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 5 of 14
  • 7. System z Measurements on DS8000 with SSDsSystem z measurements were done on DS8000 with SSDs and HDDs to compare their performance.Results are shown both for both a single SSD rank and for a large configuration with 12 SSD ranks.Figure 1 show 4KB read response times for cache hits, SSD reads, and HDD reads with short and longseeks. These results were measured by a DB2 Sync I/O benchmark.• Applications that require low response times may not be able to meet their requirement with HDDs no matter how much they short stroke their HDDs. SSDs are a good match for these applications.• Applications that traditionally use a very large storage cache may now be able to use a combination of SSDs and a small cache and save on the capital cost and power usage of the large cache.• zHPF has a lower response time than standard FICON. When performing either cache hits or I/O to SSDs, using zHPF provides a significant additional reduction in the total response time.For additional details on DB2 performance with SSDs in DS8000, see Jeffrey Berger’s paper“Accessing DB2 for z/OS on SSDs” in the CMG Journal issue 123 (Spring 2009). 9 8 8 7 Response Time(ms) 6 5 3.9 4 3 2 0.74 0.84 1 0.29 0.23 0 zHPF cache Cache hit SSD+zHPF SSD Short seek Long seek hit Figure 1 - DB2 on CKD Sync I/O Read Response Time IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 6 of 14
  • 8. The results in Figure 2 were measured by a DB2 I/O benchmark. They show random 4KB readthroughput and response times. SSD response times are very low across the curve. They are lower thanthe minimum HDD response time for all data points. 20 Response Time(ms) 15 10 5 0 0 3 6 9 12 15 18 Throughput (K IOPS) HDD Short seeks HDD Long seeks SSD Figure 2 - DB2 on CKD Random Read Throughput/Response Time CurveFigure 3 shows SSD vs. HDD performance in the following larger configurations: 1. 96 x 146GB SSDs on 6 Device Adapter(DA) pairs in 12 x 6+P RAID5 arrays. 84 SSDs are active and 12 are hot spares. 2. 96 x 146GB HDDs on 6 DA pairs in 12 x 6+P RAID5 arrays. 84 HDDs are active and 12 are hot spares. 3. 384 x 146GB HDDs on 6 DA pairs in 48 x 6+P RAID5 arrays. 360 HDDs are active and 24 are hot spares.These results show very good SSD response times all the way to 120K IOPS, where the DS8300controllers become the performance bottleneck. IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 7 of 14
  • 9. 4KB Random Read: Large Config 20 R e s p o n s e T im e ( m s ) 15 16-HPF-96SSD 10 16-HPF-96HDD 32-HPF-384HDD 5 0 0 20 40 60 80 100 120 140 Throughput (K IOPS) Figure 3 - CKD 4KB Random Read Large ConfigurationDistributed Systems MeasurementsDistributed systems measurements were done with a Power Systems server running AIX attached to aDS8000 with SSDs and HDDs. Results are shown for a single rank doing random and sequential readsand writes.Figure 4 shows distributed systems I/O response times. Note that they are similar to response times forzHPF. IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 8 of 14
  • 10. 8 8 Response Time(ms) 6 Cache Hit 4 SSD Read Miss 2 0.7 HDD 15K RPM Rd 0.14 Miss 0 Figure 4 – Distributed Systems 4KB Read Response TimeFigure 5 shows SSD response times are very low across the curve. They are lower than the minimumHDD response time for all data points. IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 9 of 14
  • 11. 15 Response Time(ms) 10 5 0 0 5 10 15 20 25 Throughput( K IOPS) 15K HDD SSD Figure 5 – Distributed Systems 4KB Random Read: SSD vs HDD on one RAID5 RankFigure 6 shows SSDs provide about the same improvement on random writes as they do on randomreads. Note that random write performance is lower than random read performance on HDD and SSDdue to the extra drive I/Os done on RAID5 writes. Each application write requires 4 drive I/Os (2 readsand 2 writes). Both the read and write SSD tests do about 20K IOPS to the SSD rank. 20 15 K IOPS 10 15K HDD SSD 5 0 Read Write Figure 6 – Distributed Systems 4KB Random IO: SSD vs HDD on one RAID5 Rank IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 10 of 14
  • 12. Figure 7 shows that the scaling from one to two ranks on the same DA pair is very good for random I/O. 40 35 30 K IOPS 25 20 One 6+P 15 Two 6+Ps 10 5 0 Read Write Figure 7 – Distributed Systems 4KB Random IO: One and Two SSD RAID5 RanksFigure 8 shows that the results are about the same for both HDDs and SSDs for sequential I/O. This isbecause the DA is the bottleneck for sequential I/O for both HDDs and SSDs. 500 400 MB/sec 300 15K HDD 200 SSD 100 0 Read Write Figure 8 – Distributed Systems Sequential I/O: SSD vs HDD on one RAID5 Rank IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 11 of 14
  • 13. Figure 9 shows that the scaling from one to two ranks on the same DA pair is also very good forsequential I/O. 1000 800 MB/sec 600 One 6+P 400 Two 6+Ps 200 0 Read Write Figure 9 – Distributed Systems Sequential I/O: One and Two SSD RAID5 RanksArray Rebuild ResultsThe array rebuild rate for an idle 6+P SSD array is 72.6 MB/sec. This is around 10-15% faster than a6+P array with 15K RPM HDDs. The faster rebuild rate lowers the risk of data loss due to a drive failureduring an array rebuild.Reliability, Energy, Cooling and SpaceIn addition to the dramatic performance advantages SSDs provide over their HDD counterparts fortransaction-intensive applications, SSDs boast other key advantages, such as higher reliability, lowerenergy usage, less cooling requirements, and the ability to reduce data center footprints. When combinedthese advantages can add up to significant performance improvements as well as a lower costs structurefor business critical applications.With no moving parts, SSDs can be more resilient than HDDs. In fact, the service life of an enterprise-class HDD is around five years. According to one popular enterprise SSD manufacturer, SSDs maydouble this with a service life of ten years. They go on to claim, “an SSD will last twice as long, onaverage, when compared to HDD. This has a huge impact on the IOPS cost over time. In a ten-yearperiod the entire HDD population would need to be replaced (on average), while none of the SSD wouldwear out.” 4 IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 12 of 14
  • 14. Since deploying SSDs can eliminate the expensive habit of “short stroking” HDDs to enable higherthroughput performance for critical applications, clients may see a considerable reduction in theirstorage footprints. Recall that “short-stroking” HDDs require clients to use a small portion of the HDDscapacity, which is the tradeoff for higher performance. By eliminating this, virtually 100% of the SSD isutilized, which can greatly reduce the number of drives needed. As clients continue to struggle withmanaging the tremendous growth of data they must manage, more efficient storage utilization can paybig dividends, especially in metropolitan areas where real estate values are at a premium.With respect to energy, each SSD uses about half of the energy of a 15K RPM HDD. For applicationsthat are able to replace large numbers of HDDs with a small number of SSDs, energy savings arecompounded.The IBM technical brief titled “IBM System z® and System Storage DS8000:Accelerating the SAP® Deposits Management Workload With Solid State Drives”5 provides an exampleof the potential power, cooling and space savings from SSDs.A brief summary of this example is included here.The SAP® Deposits Management Workload was run on 2 configurations:1. A traditional configuration using 896 HDDs2. A hybrid configuration with 96 SSDs and 96 HDDs.The hybrid SSD/HDD configuration provides the following benefits: • 22% higher throughput at 50% lower response time • 60% floor space savings • 74% electrical power and cooling savingsSummarySSDs are an emerging technology for enterprise storage clients that can show immediate benefits interms of performance as well as other operational characteristics. Given the distinct attributes and costsof SSDs and HDDs, it’s clear that both drive types will coexist for some time. This will require a strongfocus on smart data placement and the subsequent data migration, which are two strategic areas for IBMSSD solutions.SSDs have no moving parts and provide much higher throughput and much lower response times forrandom I/O than traditional spinning HDDs. They can also significantly lower operational costs in thedata center. Since SSDs currently have a substantially higher cost per GB than HDDs, they arespecifically targeted at applications that require high IOPS/GB and/or low response times and mayeliminate the practice of “short stroking” for these performance critical applications.By eliminating the seek times of their spinning counterparts and providing direct access to data, SSDsmay dramatically boost performance and allow clients to maximize drive capacity utilization. This mayenable the replacement of a large number of HDDs with a much smaller quantity of SSDs, reducingenergy consumption, cooling expenses and floor space costs. IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 13 of 14
  • 15. Appendix A: SSD in DS8000 Initial Configuration RecommendationsUse the following recommendations for configuring a DS8000 with SSDs. 1. For random I/O, SSDs provide much higher throughput at a much lower response time than HDDs. The SSDs supported in the DS8000 are so fast that the DA may become the performance bottleneck on some random workloads. It is therefore recommended to use just 16 SSDs per DA pair to get the maximum performance from each SSD. (The DS8000 supports up to 8 pairs of DAs.) 2. Using SSDs for sequential I/O does not provide a substantial increase in performance. It is recommended that SSDs not be used for data that is predominantly accessed sequentially. 3. RAID5 is currently the only supported RAID level for SSDs in the DS8000. It provides more user capacity than RAID6 or RAID10. The extra redundancy of RAID6 is not needed because SSDs are at least as reliable as 15K RPM HDDs. The extra random write performance of RAID10 is not needed because the SSDs are already more than fast enough. 4. Given SSDs current high cost/GB, configurations should typically have a mix of SSDs and HDDs, with the SSDs being used for the hottest data. 5. In general, it is not recommended to use SSDs for remote copy source volumes if the targets are HDDs unless careful capacity planning is done. The reason is that the high random write throughput capability of the SSDs may overrun the relatively slower HDDs. If the write rate on the source volumes is known to be within acceptable limits, then HDDs may be considered for the secondary.References1 IBM Corp. 2009. .IBM System Storage DS8000 Turbo seriesftp://ftp.software.ibm.com/common/ssi/pm/sp/n/tsd00374usen/TSD00374USEN.PDF2 IBM Corp. 2009. US Announcement Letter 109-120: IBM System Storage DS8000 series (Machinetypes 2421, 2422, 2423, and 2424) delivers new security, scalability, and business continuitycapabilities.http://www.ibm.com/common/ssi/cgi-bin/ssialias?infotype=AN&subtype=CA&htmlfid=897/ENUS109-120&appname=USN3 IBM Corp. 2009. Driving Business Value on Power Systems with Solid State Drives.4 STEC Inc. SSD Performance and Power Advantage.5 “IBM System z® and System Storage DS8000:Accelerating the SAP® Deposits Management Workload With Solid State Drives”http://www.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP101442 IBM® System Storage DS8000® with SSDs An In-Depth Look at SSD Performance in the DS8000© Copyright IBM Corporation 2009 All Rights Reserved Page 14 of 14

×