beyond tuning: getting the most out of your oracle application

Texas Memory Systems, Inc. - The World's Fastest Storage®

Beyond Tuning: Getting the most out of your

Oracle application

Mike Ault, Oracle Guru, TMS Inc.


Michael R. AultOracle Guru

- Nuclear Navy 6 years- Nuclear Chemist/Programmer 10 years - Kennedy Western University Graduate- Bachelors Degree Computer Science- Certified in all Oracle Versions Since 6- Oracle DBA, author, since 1990


Books by Michael R. Ault


Statspackanalyzer.com

Free Statspack/AWR Analysis

Sponsored by Texas Memory Systems

-Looks for IO bottlenecks and other configuration issues.

-Straightforward tuning advice


Introduction Ok, You’ve Tuned:

• Indexes• Partitioning• Parallel Query• Memory areas• Sort and Hash areas• OS• Bandwidth

But…Performance is still not satisfactory!


Introduction

• What now?• Tune or replace IO subsystem?


What Now?

• If you don’t have CPU or Memory Issues

• If you don’t have SQL tuning issues– Or, can’t tune due to third party issues– Or, can’t use automatic Oracle tuning– Or, automatic tuning still results in IO

stress

• Look at supplementing or replacing IO subsystem.


Basic IO Subsystems

• JBOD – Just a Bunch of Disks• Basic SAN – Stripe and Mirror or RAID5• Advanced SAN – Basic SAN plus cache, plus

hot blocking• Advanced SAN + SSD – Tiered approach with

hot files on SSD or SSD as advanced caching• Pure SSD – either DDR+Flash or Pure Flash


Problems with Striping

• Most JBOD or SAN will be fronted by a RAID controller or software such as ASM

• Stripe widths are limited to 64k in most controllers

• ASM uses 1 megabyte• Small stripe widths cause IO blocking


IO Blocking


Non-Blocking


So….

• Maximize bandwidth– More HBAs– Infiniband– Most SANs can’t utilize existing bandwidth due to disk

limits• Use luns to map hot/cold disk areas (11g ASM

does this)• Tune RAID set stripe depth to IO size• Tune to max expected IO size• Reduces blocking reads and writes

– Oracle says it doesn’t block reads– This is internal to Oracle once block is in cache– Blocking reads are due to physical issues with disk


What causes blocking?

Rotational Latency Armature Motion (positional) Latency


Other IO Issues

• Redo log issues– Solve by moving or isolating redo logs

• Archive issues– Improve tuning of archive location

• Network or Storage Network• Faster IO in archive location

• Temporary Issues– Tune sorts, GTT, Bitmap, etc.– Move temp areas to lower latency write

IO


How do I tell if My System has Issues?

• OEM, AWR or Statspack– Top waits are IO related (DB file, Log)– Average latencies in Tablespoace IO area

are >5-10 ms – Average latencies are 2-5 ms and IO

waits dominate wait profile


How do SANs Overcome These Forms of Latency?

• More disks – May not help latency• Caching into Flash or DDR – Good

until cache is flooded• Selective files (hot) moved to Flash• Hot blocks moved to faster portions

of disk – still limited to 2-5 ms


What are the Pros and Cons?

• JBOD– Pros

• Easy to implement• Easy to add capacity

– Cons• Difficult to manage• Requires third party or OS tools• Doesn’t handle hot blocks/files• Latency issues• Bandwidth issues



• Simple SAN– Pros

• Easy to manage• Easy to expand

– Cons• Requires licenses for management software• Doesn’t address hot blocks/files• Still has latency issues• Bandwidth issues



• Advanced SAN– Pros

• Relatively easy to manage• Handles hot blocks/files

– Cons• Expensive• Expensive to expand• Licensing of software and support costs• Still has latency issues• Still has bandwidth issues



• Advanced SAN with Caching – Pros

• Easy to manage• Handles hot blocking/files• Provides some relief from latency issues

– Cons• Once cache is flooded has latency issues• Expensive to implement and expand• Licensing of software• May have bandwidth issues



• Advanced San with SSD– Pros

• Easy to manage• Solves most latency issues up to a point• Solves hot blocking issues

– Cons• Expensive to implement and expand• License of software costs• Usually shoehorns SSDs into existing

architecture• Bandwidth issues



• Mixed DDR and Flash– Pros

• Tier solution for hot blocks• Usually has outstanding latency• Usually has great bandwidth• Usually Automatically managed

– Cons• Expensive due to DDR• DDR requires battery backup if used as a

storage tier• License costs



• Pure Flash– Pros

• Usually doesn’t require tiering• Great Latency• Using eMLC – Lower costs than SLC or DDR• Easily managed• Easily expanded

– Cons• More expensive than JBOD, less expensive

than Advanced SAN• Needs management software such as ASM


How About some Numbers?

IOPS Comparison for Various SANs(Source: www.storageperformance.org)


Looking Forward

• You have tuned• You have tuned the existing IO

subsystem• Performance is still borderline• How do you determine what system

should be next?


Object Intensity•Combines both throughput and capacity requirements•IOPS/GB•At a high enough IOPS/GB SSD is the cheapest solution•At a low enough IOPS/GB Capacity oriented disk drives meet the performance requirement•In between is performance optimized drives (15K RPM)


Based on performance AND price per GB

SSD

Territory

Fast HDD Territory

Capacity Oriented HDD

Territory

With eMLC the ratio is now around 1 IOPS/GB or less!


The Adjusted Storage Value Index

• Takes into account:– Cost (USD)– Warrantee (years)– Capacity (Terabytes)– Performance (IOPS)– Latency (ms) (not in original SVI)

• The higher the number, the better the value


Calculation of ASVIAdjusted Storage Value Index =

(TUC*IOPS*WY)/(cost*L)

Where:

TUC = Total usable capacity in TerabytesIOPS = Validated IOs per second (SPC-1 results

for example)WY = Warranty years (or years of paid

maintenance if added to cost)Cost = Cost of validated systemL = Latency at measured IOPS level


Comparison of Storage Values

All data taken from published SPC-1 Results

Adjusted Storage Value Index

0.0000

2.0000

4.0000

6.0000

8.0000

10.0000

12.0000

14.0000

16.0000

18.0000

20.0000

3par

Dataco

re

Fujitsu

DX8400

Hitach

i2500

Huawei S

5600

IBM

ds87

00 6n

2s

Info

rtren

d

NetApp

FAS3170

Pillar

SUN 6780

RamSan 6

20 XIO

Manufacturer

AS

VI

ASVI/Manufacturer

Summary

• Once all other tuning is done, tune IO• Low latency high bandwidth

architectures give the best performance

• Almost all advancements in SAN technology are to overcome rotating disk limitations

• Pure SSD solutions (at least at the main level) are the future


beyond tuning: getting the most out of your oracle application

Technology