Storage Performance Testing - SNIA

EDUCATION

Storage Performance Testing

Woody Hutsell, Texas Memory Systems

EDUCATION

Storage Performance Testing© 2007 Storage Networking Industry Association. All Rights Reserved.

2

SNIA Legal Notice

• The material contained in this tutorial is copyrighted by the SNIA.

• Member companies and individuals may use this material in presentations and literature under the following conditions:– Any slide or slides used must be reproduced without

modification– The SNIA must be acknowledged as source of any

material used in the body of any document containing material from these presentations.

• This presentation is a project of the SNIA Education Committee.

EDUCATION


3

Abstract

Storage Performance TestingConducting storage performance tests is essential to selecting storage for tiered storage environments. Some applications require endless hours of constant data acquisition, while others experience peak bursts of small block I/O. The best storage device for one application is almost never the right storage device for another.

This session will provide an in-depth technical discussion of storage performance testing.

EDUCATION


4

Agenda Topics

• Why test storage?• Types of storage performance testing:

– Benchmarking.– Application simulation.– Application testing.– Production testing.

• Common mistakes.

EDUCATION


5

Why Test Storage?

• Because it matters to your users and customers.– Slow storage performance means slow response times and long

running queries.

• Because it affects your batch window.– Slow storage can mean longer batch or backup windows causing

lower application availability or maintenance windows.

• Because it matters to your company’s profitability.– Slow storage can frustrate your customers and waste the

investment you have made in your server infrastructure.– Inappropriate use of fast storage means wasted dollars spent on

performance.

• Because storage vendors do not publicize every relevant metric for your application and environment.

EDUCATION


6

Types of Storage Performance Testing• Benchmarking.

– Review published and audited industry benchmarks.– Conduct tests with industry standard software.– Conduct tests for data corruption.

• Application simulation.– Use industry standard software to test a program with

conditions similar to a target application.• Application testing.

– Test an application with sample queries or scripts in a production-like environment.

• Production testing.

EDUCATION


7

Published Benchmarks

• Storage Performance Council– www.StoragePerformance.Org– SPC-1 test simulates an on-line transaction processing (OLTP)

environment.– SPC-2 test to simulate large block sequential processing.

• Spec-SFS– www.Spec.Org/sfs97r1– A good test for measuring performance of file servers and

network attached storage.

• TPC-C– www.tpc.org– TPC-C for testing OLTP, TPC-H for decision support and TPC-W

for web e-commerce.

http://www.tpc.org/

EDUCATION


8

Sample SPC-1 Result

• Shows peak SPC-1 IOPS.

• Shows response time curve.

EDUCATION


9

Benchmarking Software

• IOMeter– Most popular tool among storage vendors.– Available free from www.iometer.org.– Primarily a Windows-based tool.

• IOZone– Broad OS support.– Available free from www.iozone.org.

• Benchmark Factory for Databases by Quest Software.– TPC-B, TPC-C, TPC-D (not for publishing results).

• Vendor tools.

http://www.iometer.org/

http://www.iozone.org/

EDUCATION


10

IOMeter – Disk Targets Tab

Heuristics:•One manager per server.•One worker per processor.

Note:•If you leave this field at “0”, IOMeter will use all available disk space.

Can play a significant role in observed performance.

EDUCATION


11

IOMeter – Example Effect of Varied Outstanding I/Os

125,538

339,944

-

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

'2k' '4k' '16K' '64K' '256K'

Block Size of Transfer

IOPS

25 Outstanding IOs.

1 Outstanding IO.

EDUCATION


12

IOMeter – Setting Access Specifications

Test storage with small and large block transfer request sizes.

Try different sequential vs. random tests.

Try different read/write mixtures.

Usually leave at default but can be changed to match application behavior.

EDUCATION


13

IOMeter – Example Effect of Varied Block Sizes

-

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

'2k' '4k' '16K' '64K' '256K'


IOPS

Small block size = HighIOPS but relatively Lowbandwidth.

Big block size = LowIOPS but relatively Highbandwidth.

EDUCATION


14

IOMeter – Example Effect of Random vs. Sequential

1,413

4,626

1,000

2,000

3,000

4,000

5,000

6,000

'2k' '4k' '16K' '64K' '256K'


Sequential Transfers

Random Transfers

IOPS

EDUCATION


15

IOMeter - Scripting

• IOMeter can be used to generate scripts.• Scripts can be set-up to run through a long set of

data patterns and then record the output to a log file.

• Good for overnight testing runs of new products.• Collect these reports and use them to compare

products.• Monitor a device over time or after major

configuration changes to verify performance baseline.

EDUCATION


16

IOMeter – ScriptingExample

Name your script

Set the duration for each test iteration.

This script will increment through Outstanding I/O levels.

EDUCATION


17

Testing for Data Corruption

• Storage devices and storage network components are almost always reliable in predictable performance ranges, but the question is how do they handle extreme requirements.

• Most benchmarking tools do not automatically check data.

• Testing for data corruption usually means testing with data patterns that challenge components.– Need to test extremes of performance.– Need to test extreme data patterns.

EDUCATION


18

Case Study: Server NMIs

• Problem: Storage device was causing server NMI (crash) when other company storage does not.• Weeks were spent testing. Progress was slow because the

problem did not repeat frequently.• Key test tool: Medusa Labs software was deployed to

generate difficult data patterns for server and storage.• Resulted in nearly instant NMIs due to their challenging data

patterns (a good thing in this case because it helped diagnose the problem faster).

• Conclusion: Brand “X” HBA in PCI slot 1 caused NMIswhile the same card in PCI slot 2 did not cause NMI. Brand “Y” HBA worked fine in either PCI slot. Problem only observed under extreme loads.

EDUCATION


19

Application Simulation Testing• One type of test does not represent all

applications.• One type of application does not represent all

uses for a storage product.• Common types of application simulation testing:

– Test storage latency for messaging or other single-threaded applications.

– Test peak storage bandwidth for data acquisition or data streaming environments.

– Test peak storage IOPS for databases.

EDUCATION


20

IOMeter – Simulating Single Threaded Applications

11 Outstanding I/O simulates a single threaded

application.Note: Single threaded applications are extremely sensitive to latency (server, HBA, switch and storage device).

EDUCATION


21

IOMeter – Simulating Multi-threaded Applications

2525 Outstanding I/Os simulates a multi-threaded

application.

EDUCATION


22

IOMeter – Simulating Database Environments

8

Small transfer request size simulates

database transfers.Match the

application’s read/write

distribution.

Database activity is

mostly random.

EDUCATION


23

IOMeter – Testing Mixed Access Patterns

Name Your Access Pattern

Set % Access to resemble your application.

EDUCATION


24

IOMeter – Simulating Data Streaming

512

Big transfer request size tests peak bandwidth.

Match the application’s

read/write distribution.

A mostly sequential

setting is best.

EDUCATION


25

Application Testing

• Testing with the actual application is the best way to measure storage performance.– Production-like environment that can stress storage

limits is desirable.– Measure performance of different solutions:

• Compare OLTP response times.• Compare batch run times.• Compare sustained streaming rates.

– Operating system and application tools can help monitor storage performance.

EDUCATION


26

Case Study: Windows Storage Performance• Windows performance monitor can be used to

monitor storage performance.• Capture the following key variables over the

duration of a peak processing period or test run:– Processor: % processor time (total and by processor).– Physical disk: average disk queue (total, read and

write by disk/array).– Physical disk: disk bytes/second (total, read and write

by disk array).

EDUCATION


27

Case Study: Windows Storage Performance• Tips to analyzing Windows Performance Monitor

results:– Use the following scaling to ease visual analysis:

• Disk queues: 1:1 ratio (default is 100:1).• Processor utilization: 1:1 ratio (default is 1:1).• Disk bytes: 0000001:1 ratio (default is a .0001:1).

– Start with “total” fields and then drill down into “read/write/by disk/by processor” variables.

– Alter the line thickness to see your results easier.– Use the slider bars to zoom into trouble spots.

EDUCATION


28

Case Study: Windows Storage Performance• More tips to analyzing Windows Performance Monitor

results:– Disk bytes per second should be divided by 1024 to get disk KB

and 1024 again to get disk MB.– Where physical disk queues increase is likely at the same point

where you have hit a storage performance limitation.– A system with high processor utilization does not have a storage

performance bottleneck.– Microsoft recommends that physical disk queues greater than 3

(per disk) shows an I/O bottleneck.– Processor utilization levels off in places you have physical disk

queues this is an indication that faster storage will improve application performance.

EDUCATION


29

Case Study: Windows Storage Performance

Disk Queues show pending

requests to storage.

Disk Bytes Per Second helps reveal storage

limitations.

Processor Time shows

percent processor utilized.

EDUCATION


30

Case Study: Windows Storage Performance

No Processor bottleneck

No disk queuesLow disk

activity

EDUCATION


31

• IOStat results show read and write bytes per second:

• TOP shows CPU utilization including I/O Wait.

Monitoring Storage Performance With UNIX

Device: r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util/dev/sdb 0.00 10619.39 0.00 85570.91 16.12 4636.79 43.52 0.10 101.21/dev/sdc 0.00 10678.79 0.00 85570.91 16.07 2438.06 22.75 0.10 107.27

avg-cpu: %user %nice %sys %idle13.04 0.33 68.15 18.48

load averages: 0.09, 0.04, 0.03 16:31:0966 processes: 65 sleeping, 1 on cpuCPU states: 69.2% idle, 18.9% user, 11.9% kernel, 0.0% iowait, 0.0% swapMemory: 128M real, 4976K free, 53M swap in use, 542M swap free

EDUCATION


32

Monitoring Storage Performance With Oracle

Elapsed: 68.87 (mins)Top 5 Wait Events~~~~~~~~~~~~~~~~~ Wait % TotalEvent Waits Time (cs) Wt Time-------------------------------------------- ------------ ------------ -------db file sequential read 18,073,422 581,168 59.36db file scattered read 933,001 267,364 27.31db file parallel write 25,990 35,898 3.67SQL*Net message from dblink 181,872 20,372 2.08latch free 11,936 17,879 1.83

-------------------------------------------------------------

Tablespace------------------------------

Av Av Av Av Buffer Av BufReads Reads/s Rd(ms) Blks/Rd Writes Writes/s Waits Wt(ms)

-------------- ------- ------ ------- ------------ -------- ---------- ------SESSION_DATA

61 0 20.2 1.2 190,606 94 128,753 56.8UNDOTBS1

32 0 14.1 1.0 16,517 8 6,083 2.3

These wait events are

heavily influenced by

storage.

Tablespace metrics are a good way to

monitor storage

performance.

EDUCATION


33

• Risk vs. Reward.– Risk: taking an unsupported, well-traveled evaluation

unit and putting it in a production environment could compromise application availability and expose unexpected system problems.

– Reward: sometimes this is the only way to know for certain that storage performance is acceptable for an application.

Production Testing

EDUCATION


34

Typical Mistakes

• Testing storage performance with file copy commands.

• Comparing storage devices back-to-back without clearing server cache.

• Testing where the data set is so small the benchmark rarely goes beyond server or storage cache.

• Forgetting to monitor processor utilization during testing.

• Monitoring the wrong server’s performance.

EDUCATION


35

Continue Your SNIA Education Experience At SNW• Attend Hands-On Labs in:

Data ClassificationKey to Service Level Management

Data Security and Protection Data Assurance Solutions to Meet Corporate

RequirementsIP Storage

iSCSI, Your IP SANStorage Management

Manage Storage or Be Managed By ItStorage Virtualization

Increasing ProductivityZero to SAN

• Fibre Channel Connectivity in No Time

Sessions begin Monday afternoon, April 16 and continue through Wednesday, April 18. All sessions in Emma/Maggie/Annie, 3rd

Floor of the Hyatt Manchester.Registration at the SNW Registration area

EDUCATION


36

Q&A / Feedback• Please send any questions or comments on this presentation to

SNIA: [email protected]

Many thanks to the following individuals for their contributions to this tutorial.

SNIA Education Committee

Sarah Worthy Jamon BowenStorage Performance Council Elaine SilberChris Lionetti Rob Peglar

mailto:[email protected]

Documents

Storage Performance Testing - SNIA