perf comparo - ds8800, ds8700 & ds8300[1]

8/11/2019 Perf Comparo - DS8800, DS8700 & DS8300[1]

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IBM System Storage DS8800 Performance Whitepaper

December 2010

Andrew W. Lin

David Whitworth

Sonny E. Williams

Yan Xu

Document WP101799

Systems and Technology Group

2010, International Business Machines Corporation


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IBM DS8800 Performance

Document: WP101799 IBM Corporation Page 2 of 33

Notices, Disclaimer and TrademarksCopyright 2010 by International Business Machines Corporation.

No part of this document may be reproduced or transmitted in any form without writtenpermission from IBM Corporation. Product data has been reviewed for accuracy as of the dateof initial publication. Product data is subject to change without notice. This information may

include technical inaccuracies or typographical errors. IBM may make improvements and/orchanges in the product(s) and/or programs(s) at any time without notice. References in thisdocument to IBM products, programs, or services does not imply that IBM intends to make suchproducts, programs or services available in all countries in which IBM operates or doesbusiness. THE INFORMATION PROVIDED IN THIS DOCUMENT IS DISTRIBUTED "AS IS"WITHOUT ANY WARRANTY, EITHER EXPRESS OR IMPLIED. IBM EXPRESSLY DISCLAIMSANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE ORNON-INFRINGEMENT.

IBM shall have no responsibility to update this information. IBM products are warrantedaccording to the terms and conditions of the agreements (e.g., IBM Customer Agreement,Statement of Limited Warranty, International Program License Agreement, etc.) Under which

they are provided. IBM is not responsible for the performance or interoperability of any non-IBMproducts discussed herein. The performance data contained herein was obtained in acontrolled, isolated environment. Actual results that may be obtained in other operatingenvironments may vary significantly. While IBM has reviewed each item for accuracy in aspecific situation, there is no guarantee that the same or similar results will be obtainedelsewhere. Statements regarding IBMs future direction and intent are subject to change orwithdraw without notice, and represent goals and objectives only. The provision of theinformation contained herein is not intended to, and does not, grant any right or license underany IBM patents or copyrights. Inquiries regarding patent or copyright licenses should be made,in writing, to:

IBM Director of LicensingIBM CorporationNorth Castle DriveArmonk, NY 10504-1785U.S.A.

IBM, Enterprise Storage Server, ESCON, FICON, FlashCopy, System Storage, System z,System p, z/OS, zEnterprise, Easy Tier, and DS8000 are trademarks of International BusinessMachines Corporation in the United States, other countries, or both. Other company, productsor service names may be trademarks or service marks of others.


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Acknowledgements

The authors would like to thank the following colleagues for their comments and insight:

Lee La Frese IBM Systems & Technology Group, Tucson, AZJoseph Hyde IBM Systems & Technology Group, Tucson, AZ

Allen Marin IBM Systems & Technology Group, Boulder, CO

Vic Peltz IBM Systems & Technology Group, San Jose, CA

David Sacks IBM Systems & Technology Group, Chicago, IL

Christopher Sansone IBM Systems & Technology Group, Tucson, AZ

Leslie Sutton IBM Systems & Technology Group, Poughkeepsie, NY

A Note to the Reader

This White Paper assumes a familiarity with the general concepts of Enterprise Disk StorageSystems. Readers unfamiliar with these topics should consult the References section at theend of this paper.


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Table of Contents

Executive Summary ................................................................................................................... 51 Introduction ........................................................................................................................ 6

1.1 Audience ........................................................................................................................ 61.2 Overview of DS8800 Hardware Enhancements.............................................................. 72 Open Systems Performance .............................................................................................. 8

2.1 SPC-2 Benchmark Results............................................................................................. 82.2 Maximum Throughput Benchmarks ................................................................................ 92.3 OLTP Performance........................................................................................................10

3 Host Adapter Performance................................................................................................124 Device Adapter Performance ............................................................................................145 Drive Performance ............................................................................................................16

5.1 HDD Performance.........................................................................................................165.2 SSD Performance .........................................................................................................18

6 System z Performance ......................................................................................................22

6.1 Maximum Throughput Benchmarks ...............................................................................226.2 OLTP Performance........................................................................................................237 Copy Services Performance..............................................................................................25

7.1 FlashCopy.....................................................................................................................257.2 Metro Mirror Establish ...................................................................................................27

8 Conclusions.......................................................................................................................299 References........................................................................................................................2910 Appendix ...........................................................................................................................30


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Executive Summary

This paper describes the results of performance measurements conducted by the IBMEnterprise Storage performance team in Tucson, AZ utilizing the POWER6+ server

technology enhanced IBM

System Storage

DS8800. The main objective of this Paper is tocontrast the performance capacity of the DS8800 to that of the DS8700 and DS8300 models. Inaddition to base functionality, performance comparisons are provided for many of the keyadvanced features and functions offered by the DS8800, including;

Metro Mirror (synchronous mirroring) FlashCopy (local subsystem copy) FlashCopy SE (space-efficient local subsystem copy) zHPF (System z high performance FICON I/O protocol)

Additionally, performance capability for both Fixed Block (FB) and Count Key Data (CKD) dataformats are included in this Paper.

Compared to the DS8300, laboratory measurements show that the POWER6+ enhancedDS8800 typically can achieve as much as a 200% performance improvement for sequentialbandwidth. Additionally, transaction processing workloads used in the laboratorymeasurements achieved 25% or more improvement in I/O operations per second.

The DS8800 utilizes faster device and host adapters than previous DS8700 and DS8300models. These enhanced adapters help improve throughput and reduce read miss latency,especially with solid-state drive (SSD) technology. Laboratory measurements using SSDs inthe DS8800 have shown up to a 156% increase in IOPS (I/Os per second) compared to theequivalent DS8300 configuration. When compared to SSDs on a DS8700, up to a 49%increase in IOPS was achieved with a DS8800.

Finally, with a submission of 9,706 MBPS of aggregate sequential throughput, the DS8800ranks #1 for the industry standard SPC-2 (Storage Performance Council1) benchmark. This is200% faster than the DS8300 and 34% faster than the DS8700 on SPC-2 Aggregateperformance. Sequential bandwidth applications such as business intelligence, datawarehousing, video on demand, and critical batch processing workloads may observe asignificant elapsed time improvement.

1http://www.storageperformance.org


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1 Introduction

The IBM System Storage DS8000 series is the flagship disk storage platform within theIBM System Storage product portfolio. Introduced in October of 2010, the new DS8800 (IBM

2107 Model 951) represents the latest in this series of high-performance, high-capacity, flexible,and resilient disk storage systems. The most visible change from the DS8300 and DS8700models is the high density storage enclosure and frame design. The DS8800 provides storageenclosure support for 24 small form factor (SFF), 2.5", 6 Gbps (gigabits per second) serial-attached SCSI (SAS) drives in 2U (rack unit) of rack space. This new compact design enableshigher scalability, significant footprint reduction, and greater energy savings as compared toprevious enclosures which only supported 32 drives in 3.5U of rack space. The most notablechanges that enhance performance of the DS8800 include:

8 Gbps PCIe Host Adapter (HA)

8 Gbps PCIe RAID Device Adapters (DA)

Both the DS8800 and the DS8700 utilize the next generation IBM POWER6 processor withintheir Central Electronics Complex (CEC) and have replaced the RIO-G I/O enclosure, used onthe DS8300, with the Peripheral Component Interconnect Express (PCIe) I/O enclosure.Additionally, the POWER6 CEC in the DS8800 is based on the ultra-high frequency, dual-corePOWER6+ processor technology, which at 5.0 GHz is one of the industry leaders inperformance, scalability, and modularity.

The DS8800 delivers unprecedented performance and capacity growth while drawing upon therich design heritage of previous DS8000 Storage Systems. The DS8800 is a well-balancedgeneral purpose storage system that is equally at ease with bandwidth-intensive workloads, I/O-intensive workloads with low I/O latency requirements. Compared to the performance of theprevious DS8000 system, the DS8700, the new processor, 8Gbps Host Adapters and 8Gbps

Device adapters aids the DS8800 in achieving sequential read bandwidth performanceimprovement of up to 20% and sequential write bandwidth performance improvement of up to40%. Compared to the DS8300, the DS8800 achieves as much as a 200% bandwidthimprovement for sequential workloads. Additionally, transaction processing workloads achieveas much as 25% or more performance improvement, compared to the DS8300 model.

The DS8800 is available with either a pair of POWER6+ 2-way processor complex or a pair ofPOWER6+ 4-way processor complex. The measurement data in this paper reflectsperformance of the POWER6+ 4-way model.

1.1 Audience

This technical paper was developed to assist IBM and IBM Business Partner field salesrepresentatives and technical specialists in understanding the performance characteristics ofthe IBM 2107 Model 951 by contrasting the performance with that of the IBM 2107 Model 941and the IBM 2107 Model 932. The IBM 2107 Model 932 is the DS8300, POWER5+ Turbomodel; the IBM2107 Model 941 is the DS8700, POWER6 model. In this paper the IBM 2107Model 951 will be referred to as the DS8800, the IBM 2107 Model 941 will be referred to as theDS8700 while the IBM 2107 Model 932 will be referred to as the DS8300.


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1.2 Overview of DS8800 Hardware Enhancements

The following hardware enhancements have been incorporated in the new DS8800:

CEC:

The DS8800 utilizes the POWER6+, 5.0 GHz dual-core processor in its CEC, as opposed to theDS8700, which uses the POWER6, 4.7 GHz dual-core processor.

8 Gbps Host Adapters:

The DS8800 model offers enhanced connectivity with 4-port and 8-port fibre-channel (FC) /FICON host adapters. The advanced host adapters support 8 Gbps, as opposed to 4 Gbps onthe DS8700 and DS8300, and offer up to 100% improvement in single-port throughputperformance and up to 400% improvement in single adapter (e.g. 4-port) throughputperformance. This can help deliver not only faster performance but also cost savings by

enabling a potential reduction in the number of host ports needed to support a given level ofperformance.

The new host adapters support FICON attachment to FICON Express8 on zEnterprise 196(z196) and System z10 (z10 EC, z10 BC).

8 Gbps Device Adapters:

The DS8800 offers 8 Gbps device adapters, as opposed to 2 Gbps on the DS8700 andDS8300. These adapters are designed to provide improved IOPS performance, throughput, andscalability. They are optimized for SSD technology architected to support scalability growth overthe long term. These capabilities complement the Power6+ server family to help provide

significant performance enhancements.

High-Density Storage Enclosure:

The DS8800 provides storage enclosure support for 24 SFF, 2.5", 6 Gbps SAS drives in 2U ofrack space, as opposed to 3.5, 3 Gbps on the DS8700 and DS8300. The smaller and moreefficient drives help improve the storage density for drives as compared to previous enclosures,which support 32 drives in 3.5U of rack space.

Improved High-Density Frame Design:

The DS8800 can support a total of 1056 drives in a smaller footprint (three frames, as opposed

to 1024 drives in five frames on the DS8700 and DS8300), thereby supporting higher densityand helping to preserve valuable raised floor space in data center environments. The DS8800 isdesigned to leverage best practices with hot/cold aisle data center design, drawing air forcooling from the front of the rack and exhausting hot air at the rear of the rack. Coupled with thisimproved cooling implementation, the reduced system footprint, and small form factor SAS-2drives, a fully configured DS8800 consumes up to 40% less power than previous generations ofDS8000. The DS8800 base model supports up to 240 drives, with the first expansion framesupporting up to 336 drives and second expansion frame supporting up to 480 drives.


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2 Open Systems Performance

The following section describes the results of various Open Systems performancemeasurements and draws a comparison among the DS8800, DS8700 and the DS8300. A

detailed description of the configuration for these measurements can be found in Appendix B.

2.1 SPC-2 Benchmark Results

IBM has long been a strong proponent and supporter of the industry-standard benchmarksdeveloped by the Storage Performance Council for illustration of an objective measure ofstorage system performance capabilities. An SPC-2 result for the DS8800 was published inDecember of 2010. As of the publication date of this paper, DS8800 owns the leading SPC-2result for scale up disk storage.

SPC-2 is designed to emulate applications that read and write large blocks of data in asequential manner. Examples of these classes of applications include archival, backup,

business intelligence, and video streaming. The SPC-2 benchmark consists of three workloadsas well as a composite score that aggregates all of the workload results into a single metric.

Figure 4 summarizes the SPC-2 results for the DS8800 and compares them to the publishedSPC-2 benchmark results for DS8300 and DS8700.

0

2,000

4,000

6,000

8,000

10,000

12,000

MBPS

DS8300 (non-

Turbo)

DS8700 DS8800

Published SPC-2 Comparison

Large File Processing

Large Database Query

Video on Demand

SPC-2 Aggregate

Figure 4: SPC-2 results for DS8300, DS8700 and DS8800

The DS8800 is 200% faster than the DS8300 and 34% faster than the DS8700 on SPC-2Aggregate performance.


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2.2 Maximum Throughput Benchmarks

For a benchmark utilizing 4KB reads or writes and a 100% cache hit ratio, the DS8800 showsabout a 5% improvement in throughput over the DS8700. Cache Hit workloads show how fastdata can be moved to or from the systems cache. Since the system is retrieving the data from

cache, rather than the disk drives on the backend, this measurement is useful in determining theperformance difference in the systems host adapters and processors. The 5% gain achieved isprimarily a result of the upgrade from the POWER6 processor in the DS8700 to the POWER6+processor in the DS8800. However, cache hit performance does not reflect the full picture ofthe performance capabilities of a storage system, but rather provides a starting point tounderstanding the gains that may be attainable by the system. Measurements illustrated in thefollowing sections will help complete that picture using workloads reflective of real productionsystems.

Production systems virtually never exhibit 100% cache hits, but typically feature somecombination of disk and cache accesses. Therefore, the systems cache miss performance isalso of interest. With the Cache Hit workload, the DS8800 boasts an improvement of about 5%

over the DS8700 for 4KB reads and writes with cache miss operations. The 5% improvement ismostly due to the upgraded POWER6+ processor. This balanced improvement in performancebetween cache misses and cache hits for reads and writes is important. It suggests that typicalonline transaction processing (OLTP) workloads will improve in a consistent manner whenmigrated to DS8800 regardless of the workload mix.

Sequential workloads will generally stress the internal data paths and disk adapters in a storagesystem. In Figure 1, we see that the new DS8800 device adapters provide substantialimprovements the DS8700 and huge improvements over the DS8300s adapters.Measurements showed a gain of 22% for Sequential Reads and 42% for Sequential Writes forthe DS8800 versus the DS8700. The DS8800 is 200% faster than the DS8300 on bothSequential Reads and Writes.

0.0

2.0

4.0

6.0

8.0

10.0

12.0

GBPS

Bandwidth

64KB Sequential Reads

DS8800 DS8700 DS8300

0.0

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6.0

9.0

GBPS

Bandwidth

64KB Sequential Writes

DS8800 DS8700 DS8300

Figure 1: DS8800 vs. DS8700 vs. DS8300, Open systems Sequential IO

To realize the performance gains shown in Figure 1 a total of 8 DA-Pairs were used. Withnormal configuration rules this requires a system with at least 432 drives.


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0.0

4.0

8.0

12.0

16.0

20.0

0 20 40 60 80 100 120 140 160 180 200I/O Rate (KIOPS)

Response

Time(ms)

DS8800 - 16 HA, 768 HDD DS8700 - 32 HA, 992 HDDDS8700 - 32 HA, 512 HDD DS8300 - 16 HA, 512 HDD

2.3 OLTP Performance

Online Transaction Processing workloads are designed to represent the type of mixed I/Opatterns seen in online applications. They are composed of a mixture of both reads and writes

with some cache hits and some cache misses. These workloads access data primarily in arandom fashion. Figure 2 compares the measured performance of the DS8800 against theDS8700 and the DS8300 with a Database for Open systems (DBO) workload which representsa typical OLTP environment. This workload is also referred to as 70/30/50 because it iscomposed of 70% reads, 30% writes, and 50% read cache hits.

Figure 2: DS8800 vs. DS8700 vs. DS8300, 4KB DB Open (70/30/50)

In Figure 2 we see the benefit from the upgraded processor resulting in better performance witha DS8800 than with a DS8700 despite the DS8800 having fewer drives and host adapters thanthe DS8700.

In Figure 3, we see a similar comparison using the 50/50/50 workload, which is much like the70/30/50 OLTP workload but with a higher proportion of writes, i.e. 50% writes andconsequently 50% reads. The basic result is similar although in this case the DS8700sadditional drives provide slightly better response times than measured on the DS8800 at some

data points. The DS8700 tested had 992 drives and 32 host adapters while the DS8800 had768 drives and 16 host adapters.


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0.0

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8.0

12.0

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20.0

0 20 40 60 80 100 120 140 160 180 200

I/O Rate (KIOPS)

ResponseTime

(ms)

DS8800 - 16 HA, 768 HDD DS8700 - 32 HA, 992 HDDDS8700 - 32 HA, 512 HDD DS8300 - 16 HA, 512 HDD

Figure 3: DS8800 vs. DS8700 vs. DS8300, 4KB 50/50/50


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3 Host Adapter Performance

The host adapter hardware in the DS8800 now features an 8 Gbps FCP and FICONinfrastructure as opposed to 4 Gbps on the DS8700/DS8300.

Figure 5 shows the measured gains in single port throughput performance of the DS8800 overprevious models. Here we see incremental performance gains of up to 108% for a single portfor read and write IOPS and an improvement up to 162% for a single HA. Significant bandwidthperformance increases are also shown in Figure 6. Single port bandwidth has increased atleast 100% to over 800 MBPS for both sequential read and write throughput. That increasetranslates into at least a 255% improvement when comparing a single 8 Gbps HA on theDS8800 as opposed to the DS8700s 4 Gbps HA.

0

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200

KIOPS

SinglePo

rtRe

adHit

SinglePo

rtW

riteH

it

SingleH

ARe

adHit

SingleH

AW

riteH

it

DS8800 DS8700 DS8300

Figure 5: DS8800 vs. DS8700 vs. DS8300, Open HA 4KB IOPS Performance


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0.0

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MBPS

SinglePo

rtSe

qRead

SinglePo

rtSe

qWrite

Single

HASeqR

ead

SingleHA

SeqW

rite

DS8800 DS8700 DS8300

Figure 6: DS8800 vs. DS8700 vs. DS8300, Open HA 64KB Bandwidth Performance


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010

20

30

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50

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7080

KIOPS

Read Write

DA-Pair DS8800

DA-Pair DS8700

DA-Pair DS8300

Single DA DS8800

Single DA DS8700

Single DA DS8300

4 Device Adapter Performance

Solid State Drives can sustain significantly higher random IO rates than traditional spinning harddisk drives (HDDs). When using SSDs with small block random workloads, the device adapters

are more likely to become the bottleneck than the drives themselves. Consequently,measurements were taken with SSDs to demonstrate the random IO rate performance of theDAs used in the DS8800. A detailed description of the configuration for these measurementscan be found in Appendix B.

Figures 7 shows read and write performance measured on both a single DA and on a DA pair.Here we see significant gains in small block random I/O performance for both reads and writeswhen comparing the DS8800 DA to the DS8700 and DS8300 DAs. The DA pair measurementsshow a 37% gain in read throughput and a 49% gain in write throughput for the DS8800 versusthe DS8700 while the single DA measurements show a 71% and 80% gain in read and writethroughput respectively.

Figure 7: DS8800 vs. DS8700 vs. DS8300, Device Adapter with SSDs, 4KB Random IO

DA sequential performance is shown in Figure 8. The DA pair measurements show a 175%gain in sequential read bandwidth and a 191% gain is sequential write bandwidth for theDS8800 versus the DS8700. For a single DA, the gains for sequential read and write bandwidthare 175% and 210% respectively. HDDs were used for these measurements. SSDperformance on these tests is about the same as with HDDs because the bottleneck is the DAs

bandwidth capability and not the drives.


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0

500

1,000

1,5002,000

2,500

3,000

3,500

MBPS

Read Write

DA-Pair DS8800

DA-Pair DS8700DA-Pair DS8300

Single DA DS8800

Single DA DS8700

Single DA DS8300

Figure 8: DS8800 vs. DS8700 vs. DS8300, Device Adapter with SSDs, 64KB Sequential IO


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5 Drive Performance

The DS8800 supports three SFF-2.5 SAS hard drive models: 146GB 15K RPM, 450GB 10KRPM, and 600 GB 10K RPM. It also supports SFF 2.5 300GB SSDs. A detailed description of

the configuration for these measurements can be found in Appendix B.

5.1 HDD Performance

Figures 9-11 show the performance of a single rank with available RAID configurations of the2.5 drives on a DS8800 and 15K RPM 3.5 fibre-channel drives on previous models. Whencomparing the large form factor (LFF) DS8700 15K RPM drives against the small form factor(SFF) DS8800 15K RPM drives for 4KB random reads, the DS8800 performed 13%-22% better,while the DS8800 with the SFF 10K RPM drives performed 17-26% worse. However, for typicalOLTP-like workloads, we expect the performance between SFF 15K and LFF 15K drives to besimilar. For 4KB random writes, both SFF 15K RPM and 10K drives had 15-20% and 26-28%less throughput respectively than the LFF 15K RPM drives in the DS8700. For sequential read

and write performance, both SFF 15K RPM and 10K RPM drives had equal or betterperformance than that of the LFF 15K RPM drives, primarily aided by the DS8800s 8GbpsDevice Adapters

Figure 9: 15K/10K RPM 2.5 vs. 15K RPM 3.5 Drives, 4KB Random Reads and Writes

Figure 10: 15K/10K RPM 2.5 vs. 15K RPM 3.5 Drives, Sequential Reads and Writes

Figure 11 shows 4KB random read throughput and response time curves. The SFF 15K driveshad better response time and higher throughput than LFF 15K drives.

0

1,000

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IOPS

RAID-6 RAID-5 RAID-10

4KB Random Reads

15K/2.5" 10K/2.5" 15K/3.5"

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4KB Random Writes

15K/2.5" 10K/2.5" 15K/3.5"

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15K/2.5" 10K/2.5" 15K/3.5"

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15K/2.5" 10K/2.5" 15K/3.5"


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0.0

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0 500 1,000 1,500 2,000 2,500

I/O Rate (IOPS)

ResponseTim

e(ms)

15K/2.5" 10K/2.5" 15K/3.5"

Figure 11: 15K/10K RPM 2.5 vs. 15K RPM 3.5 Drives, 4KB Random Reads, RAID-5 6+p

In general, the 15K 2.5 drives had better performance than 15K 3.5 drives, except for 4KBRandom Writes. The 10K 2.5 drives had excellent Sequential performance, but had lowerRandom Read and Write performance as expected due to the lower rotational speed.

Array rebuild results are shown in Figure 12. Both 15K and 10K 2.5 drives had better rebuildrate than 15K 3.5 drives, which is shown with better sequential read and write performance in

Figure 12. The workload used for rebuild was an OLTP-like workload.

0.0

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80.0

100.0

RebuildRate

(MBPS)

No Workload Moderate

Workload

Heavy Workload

15K/2.5" 10K/2.5" 15K/3.5"

Figure 12: 15K/10K RPM 2.5 vs. 15K RPM 3.5 Drives, Rebuild Rate, RAID-5 6+p


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5.2 SSD Performance

Solid-state drives can support significantly larger workloads than traditional spinning hard diskdrives. As shown in Figure 13, significant gains were seen in small block random I/Operformance for both reads and writes when comparing 2.5 SSDs in the DS8800 to 3.5SSDs

in the DS8700. The improvement was about 71% in both read and write throughput.

0

10

20

30

40

50

KIOPS

4KB Random Read 4KB Random Write

SFF 2.5" LFF 3.5"

Figure 13: 2.5 300GB SSDs on DS8800 vs. 3.5 SSDs on DS8700, 4KB Random IO

The Sequential performance of SSD drives is shown in Figure 14. The measurements hereshow a gain of 27% in sequential read bandwidth for 2.5 SSDs versus 3.5 SSDs in theDS8700. For sequential write bandwidth, the performance of 2.5 and 3.5 SSDs wereequivalent.


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0.0

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0 5,000 10,000 15,000 20,000 25,000

I/O Rate (IOPS)

VolumeResponseTime(ms)

SFF 2.5" 100% Read Miss SFF 2.5" 50% Read/WriteLFF 3.5" 100% Read Miss LFF 3.5" 50% Read/Write

Figure 16: 300GB/DS8800 vs. 146GB/DS8700, Single Rank (RAID-5)

Large Block Random IO (56 to 64KB)

An important observation from these results is that the performance improvement with SSDs forlarge block writes is not as remarkable as seen with just reads or with small block I/O in general.For example, while SSDs provide about 20 times the throughput of 15 KRPM HDDs for 4KBreads, the difference is only about 2 times for large block writes. This is a property of EnterpriseSSDs and not specific to the DS8000. Thus the best use cases for SSDs tend to be small blockI/Os that have a higher percentage of reads.

Figure 17 shows a single SSD array rebuild rate. The 2.5 SSDs in the DS8800 demonstratedbetter rebuild rates than the 3.5 SSDs with or without host workload. The workload used duringrebuild was OLTP-like.


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0.0

20.0

40.060.0

80.0

100.0

Rebuild

rate

(MBP

S)

No Workload Moderate

Workload

Heavy

Workload

SFF 2.5" LFF 2.5"

Figure 17: 2.5 300GB SSDs on DS8800 vs. 3.5 SSDs on DS8700,

Rebuild Rate, RAID-5 6+p


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6 System z Performance

The following section describes the results of various System z performance measurements anddraws a comparison between the DS8800 and both the DS8700 and the DS8300. A fulldescription of each workload used can be found in Appendix A. A detailed description of the

configuration for these measurements can be found in Appendix B. The term CKD belowrefers to the data format of disk subsystems attached to System z hosts.

6.1 Maximum Throughput Benchmarks

The DS8800 showed improvement for 4KB Read and Write Hit benchmarks compared to theDS8700 due to use of the new and POWER6+ processors. Testing showed gains of 5% to 10%from the DS8700 to the DS8800 for cache hits using both zHPF and traditional FICON protocol.Cache miss benchmarks on the DS8800 also yielded gains over the DS8700. Testing of 4KBRead and Write Miss performance showed a gain of up to about 14% in terms of IOPS using

both zHPF and FICON protocol.

The large block Sequential Read and Write benchmarks best exploit the systems internal PCIefabric as seen in Figure 18. For sequential performance, our testing showed a 15%improvement for reads and a 7% improvement for writes on the DS8800 compared to theDS8700.

0.0

4.0

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12.0

GBPS

Bandwidth

6x27KB Sequential Reads

DS8800 DS8700 DS8300

0.0

2.0

4.0

6.0

GBPS

Bandwidth

6x27KB Sequential Writes

DS8800 DS8700 DS8300

Figure 18: DS8800 vs. DS8700 vs. DS8300, System z Sequential IO

161% over

DS8300

171% over

DS8300


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0.0

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I/O Rate (KIOPS)

ResponseTime(ms)

DS8800 zHPF - 16 HA, 384 HDD DS8700 zHPF - 32 HA, 512 HDD

DS8800 FICON - 16 HA, 384 HDD DS8700 FICON - 32 HA, 512 HDD

6.2 OLTP Performance

Figure 19 compares the measured performance results of the DS8800 with that of the DS8700for the Database for System z (DBz) workload. This workload is designed to be comparable to

online-transaction processing. With the DBz workload, we observed an improvement inthroughput of about 4% from the DS8700, which is achieved with fewer drives and hostadapters but the same number of host channels.

Figure 19: DS8800 vs. DS8700, CKD 4KB DBz

Figure 20 also shows the results for DBz for the DS8800 compared to the DS8300. Theperformance improvement in this comparison is 24% using zHPF and 47% using FICON. ThePOWER6+ processors in the DS8800 are the main contributors to the significant increase inthroughput compared to the DS8300.


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0.0

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I/O Rate (KIOPS)

ResponseTime(ms)

DS8800 zHPF - 16 HA, 384 HDD DS8300 zHPF - 16 HA, 512 HDD

DS8800 FICON - 16 HA, 384 HDD DS8300 FICON - 16 HA, 512 HDD

Figure 20: DS8800 vs. DS8300, CKD 4KB DBz


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7 Copy Services Performance

The following section describes the results of various Copy Services performancemeasurements and draws a comparison among the DS8800, the DS8700 and the DS8300. A

detailed description of the each workload can be found in Appendix A. A detailed description ofthe configuration for these measurements can be found in Appendix B.

7.1 FlashCopy

Both FlashCopy and Space Efficient FlashCopy performance were examined using a System z(CKD) environment. For FlashCopy performance for Open systems, we observed equal orbetter performance to that of System z. For an explanation of these two versions of FlashCopy,please see Appendix C.

For single volume Background Copy, results from the DS8800 showed a 10% improvementover the DS8700 and over 77% improvement when compared to the DS8300. A full-boxBackground Copy with 8 DA-Pairs (with 48 ranks in DS8800 and 64 ranks in DS8700/DS8300)was also executed and the DS8800 was a 50% improvement over the DS8700 and a 90%improvement over the DS8300. Lab measurements show near linear scaling from 2 DA-Pairs to8-DA Pair configurations. The improvement on the DS8800 from DS8700 benefited from fasterDevice Adapters. Background Copy results are shown in Figure 21.

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Figure 21: DS8800 vs. DS8700 vs. DS8300, FlashCopy Background Copy

Figure 22 shows the host performance results of running DBz at 60% of the maximumthroughput seen in section 6.2 with either FlashCopy or Space Efficient FlashCopy configuredon the DS8800. The Copy-Source-to-Target performance for this workload showed nosignificant difference between the DS8800 and the DS8700 with 8 DA Pairs. With 6 DA Pairs,the DS8700 performed at least 34% better than the DS8300 for 6 DA Pairs. The chart alsoindicates that for this workload on the DS8700, some incremental improvement in throughputwas observed comparing 8 DA pairs with 6 DA Pairs when running with or without FlashCopy.However, Space Efficient FlashCopy does not show benefit for this workload from additional DApairs. On the DS8300 and DS8800, measurements with both 8 DA pairs and 6 DA Pairs are notavailable, however, it is expected that a similar amount of change in DBz throughput would beobserved with 8 DA pairs verses 6 DA pairs as was seen with the DS8700.


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0

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No FlashCopy Standard

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Figure 22: DS8800 vs. DS8700 vs. DS8300, FlashCopy 4KB DBz at 60% Max Throughput

Results of running a Sequential Write workload with FlashCopy active is shown in Figure 23.With 8 DA Pairs, the Copy-Source-to-Target measured performance is 14% higher forFlashCopy volumes and 9% higher for Space Efficient FlashCopy volumes on the DS8800 thanon the DS8700. Similar tests were done on the DS8700 and DS8300 with 6 DA Pairs, theperformance is 48% higher for FlashCopy volumes and 37% higher for Space EfficientFlashCopy volumes on the DS8700 than on the DS8300. Figure 23 also shows performanceimprovement on the DS8700 when using 8 DA Pairs versus 6 DA Pairs. Althoughmeasurements are not available, it is likely that similar improvement in Sequential Writethroughput would be seen when comparing 8 DA Pairs with 6 DA Pairs on both the DS8800 andthe DS8300.

Keep in mind that this is a very intensive worst case FlashCopy environment where each hostI/O causes data to be moved in the background because all of them are sequential writes to thesource volumes. Typical production environments would likely see much less of an effect onhost throughput due to FlashCopy. This also reinforces that Space Efficient FlashCopy is not agood use case for workloads where the source volumes will be subjected to heavy sequentialwrites.


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0.0

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GBPS

No FlashCopy Standard FlashCopy Space Efficient

FlashCopy



Figure 23: DS8800 vs. DS8700 vs. DS8300, FlashCopy 6x27K Sequential Write

Figure 24 is intended to simulate a typical customer application. This test is designed tovalidate that host sequential reads and background copies may coexist on a RAID rank withoutone dominating the other. Individually, single volume Background Copy improved 9% and 77%respectively when comparing with results on the DS8700 and DS8300. Single streamsequential read increased 22% and 71% respectively versus the DS8700 and DS8300. Whenrunning the two tasks concurrently, the performance improvement was 36% and 72% inBackground-Copy and 59% and 73% in Sequential Read respectively on the DS8800 ascompared to the same experiment measured on the DS8700 and DS8300.

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Figure 24: DS8800 vs. DS8700 vs. DS8300, Background Copy with

Concurrent Sequential Read

7.2 Metro Mirror Establish

Figure 25 shows the comparison of Metro Mirror establish bandwidth between the DS8800 andthe DS8700/DS8300. For these tests, the data link between the two DS8800s orDS8700/DS8300s was a direct connection. With the new 8 Gbps Host Adapters, Metro Mirrorestablish bandwidth of the DS8800 was improved over 70% when comparing with


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0.0

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DS8800 DS8700/DS8300

measurements from the DS8700/DS8300. Good scaling of bandwidth over number ofconnected paths was seen for both the DS8800 and the DS8700/DS8300. This good scalingwould facilitate data migration from one DS8800 or DS8700/DS8300 to another when acustomer uses more Metro Mirror paths.

Figure 25: DS8800 vs. DS8700/DS8300, Metro Mirror Establish Bandwidth


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8 Conclusions

The DS8800 is the next chapter in IBMs flagship enterprise disk platform. Built on 50+ years ofenterprise class innovation, the new DS8800 enables much higher performance and scalability,

while preserving client investments in prior DS8000 models.

Additionally, the DS8800 illustrates IBMs focus on constant improvement of technology andperformance of its storage products. The DS8800 offers:

Faster processor speeds that result in unprecedented performance and capacity growthwhile drawing upon the rich heritage of previous DS8000 Storage Systems.

Faster adapters and buses which enable the DS8800 to achieve world class sequentialbandwidth. The SPC-2 benchmark results are ranked #1 overall.

A well-balanced general purpose storage system that can effectively support bandwidth-intensive workloads and I/O-intensive workloads.

9 References

[1] La Frese, L., Lin, A., Martin, J., Williams, S., and Xu, Y. IBM System StorageDS8700 Performance Whitepaper. August 2010.

[2] La Frese, L., Sutton, L., and Whitworth, D. IBM System Storage DS8000 with SSDs:An In-Depth Look at SSD Performance in the DS8000. April 2009.

[3] Roll, M. Understanding Storage Performance: Concepts, Issues and FAQ. 2006.

[4] Lin, A., and Peltz, V. IBM Global Mirror Performance Study. August 2009.

[5] La Frese, L., Hossain, K., Hyde, J., Lin, A., McNutt, B., Sansone, C., Sutton, L., Xu, Y.,Zhang, Y. IBM System Storage DS8700 Performance with Easy Tier. May2010.


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10 Appendix

10.A Appendix A: Workload Characteristics

Read Hit (WH): 100% Random read requests to cache. A "read hit" test issues readrequests repeatedly to a small group of blocks or records. The number of affected blocksis small enough to ensure that the entire set can be retained in cache at the same time.Hence, all requests in the read hit test are serviced out of cache. Read Hit testsgenerally give the highest I/O rate for a storage system.

Read Miss (WM): 100% Random read requests to disk. A "read miss" test issues readrequests at random across a storage area much larger than the available cache size.This test is designed in such a way that the probability of finding the requested data incache is nearly zero. Read Miss tests usually serve engineering purposes and are nottypical of customer environments.

Write Hit (WH): 100% Random write requests to cache. A "write hit" test issues writerequests repeatedly to a small group of blocks or records. The number of written blocksis small enough to ensure that the entire set can be retained in cache at the same time.It is possible that the controller may defer all destaging until after the completion of a"write hit" test. This allows throughput on the front end to be isolated and benchmarked.These types of workloads are for engineering purposes and are not typical of customerenvironments.

Write Miss (WM): 100% Random write requests to disk. A "write miss" test issues writerequests at random across a storage area much larger than the available cache size.This test is designed in such a way that the probability of writing a block a second time,before that block has been destaged from cache, is almost zero. For this reason, thenumber of destage operations is approximately equal to the number of writes.

10.A.1 Open Workloads

70/30/50: An open workload that is similar to typical OLTP applications. Itscharacterized by 70% reads, 30% writes, a 50% read hit ratio, an approximate destagerate of 17% of all I/Os and a 4KB block transfer size.

50/50/50: An open workload that is similar to very write-intensive OLTP applications. Itscharacterized by 50% reads, 50% writes, a 50% read hit ratio, an approximate destagerate of 17% of all I/Os and a 4KB block transfer size.

Sequential: Open Sequential workloads provide for reading or writing data records insequential order, one after the other. They are either 100% reads or writes using 64KBblock data transfers to disk, similar to data warehouse scan/load operations. 256K and 1MB large transfer block sizes have also been used, similar to video imaging operations.

10.A.2 System z workloads

DB z/OS: DB z/OS (formerly known as Cache Standard) is a System z workload thatsimulates a typical OLTP environment on the mainframe. Its characterized by 75%reads, 25% writes, a 4KB block transfer size and skewed I/O rates to different volumes.DB z/OS has a cache read hit ratio that varies with the configurations cache tobackstore ratio, but a frequently used value is 72%. The destage rate is not constant, butcommon values are between 14 - 17% of all I/Os.


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Cache Hostile: This workload is characterized by 67% reads, 33% writes, skewed I/Oand a 4KB block transfer size. It has a write destage rate of 50% and a destage rate of18.3% of all I/Os. The cache read hit ratio is adjustable depending on testingrequirements and the cache/backstore ratio.

Cache Friendly: This workload is characterized by 83% reads, 17% writes, skewed I/Oand a 4KB block transfer size. It has a write destage rate of 50% and a destage rate of

7.5% of all I/Os. The cache read hit ratio is adjustable depending on testingrequirements and the cache/backstore ratio, but generally uses a value of 83%.

Sequential: These workloads are similar to typical batch processing. 100% Read or100% Write, 6 x 27K transfers as indicated to/from disk with a sequential access pattern.


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10.B Appendix B: DS8800 Hardware Configurations

10.B.1 Configuration for Open Systems Measurements

RAID-5 measurements were taken with a total of up to 768 146GB 15K RPM drives. 256 GB cache, 16 Host Adapters.

Host workloads were run on an IBM Power 770 host (AIX 6.1.4.0) with 16 8Gb FibreChannels.

10.B.2 Configuration for System z Measurements

RAID-5 measurements were taken with 384 146 GB 15K RPM drives.

256 GB cache, 16 Host Adapters. Host workloads were run on a System z 2097 with 32 8Gb Fibre Channels.

10.B.3 Configuration for Drive Performance Measurements

2.5 15K RPM HDDs are of size 146GB.

2.5 10K RPM HDDs are of size 600GB.

3.5 15K RPM HDDs are of size 300GB, 450GB, or 600GB.

2.5 SSDs are of size 300GB.

3.5 SSDs are of size 146GB or 600GB.

10.B.4 Configuration for FlashCopy

384 146 GB RPM drives across 8 DA-Pairs were used for source volumes and another384 146 GB RPM drives across the same 8 DA-Pairs were used for target volumes.

256 GB cache, 16 Host Adapters.

Host workloads were run on a System z 2097 with 32 8Gb Fibre Channels.


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10.C Appendix C: Definitions and Methodologies

Open system: Sometimes referred to as distributed systems, often attached to anAIX/UNIX host and uses the Fixed Block data format.

System z: Attached to a z/OS host and uses the CKD data format. SCSI: Small Computer System Interface. A set of standards for physically connecting

and transferring data between computers and peripheral devices.

IOPS: input/output operations per second.

RAID-5: A popular RAID implementation that optimizes cost effective performance whileemphasizing use of available capacity through data striping. RAID-5 provides faulttolerance for one failed disk drive. This scheme uses XOR parity for redundancy. Data isstriped across all drives in the array and parity is distributed across all the drives.

RAID-10: Combines two schemes: RAID-0 (data striping) and RAID-1 (mirroring).Volume data is striped across several drives and the first set of disk drives is mirrored toan identical set. Since redundancy is achieved through mirroring, there is no parity inRAID-10. RAID-10 optimizes high performance while maintaining fault tolerance for disk

drive failures. It can tolerate at least one, and in most cases, multiple disk failures. FlashCopy: Uses normal volumes as target volumes for FlashCopy. These target

volumes have the same size (or larger) as their corresponding source volumes.

Space Efficient FlashCopy (SEFC): Uses volumes formatted for SEFC as the targetvolumes for FlashCopy. These volumes, known as Space Efficient volumes, have avirtual size equal to the source volume size. However, physical space is not allocated forSpace Efficient volumes when the volumes are created and the FlashCopy initiated.Instead, space is allocated in a Repository when the first update is made to originaltracks on the source volumes and the tracks are copied to the SEFC target volume.Writes to the SEFC target will also consume Repository space. Space EfficientFlashCopy can be a cost-effective method for replicating data locally.

perf comparo - ds8800, ds8700 & ds8300[1]

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