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.
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
Books by Michael R. Ault
Texas Memory Systems, Inc. - The World's Fastest Storage®
Statspackanalyzer.com
Free Statspack/AWR Analysis
Sponsored by Texas Memory Systems
-Looks for IO bottlenecks and other configuration issues.
-Straightforward tuning advice
Texas Memory Systems, Inc. - The World's Fastest Storage®
Introduction Ok, You’ve Tuned:
• Indexes• Partitioning• Parallel Query• Memory areas• Sort and Hash areas• OS• Bandwidth
But…Performance is still not satisfactory!
Texas Memory Systems, Inc. - The World's Fastest Storage®
Introduction
• What now?• Tune or replace IO subsystem?
Texas Memory Systems, Inc. - The World's Fastest Storage®
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.
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
IO Blocking
Texas Memory Systems, Inc. - The World's Fastest Storage®
Non-Blocking
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
What causes blocking?
Rotational Latency Armature Motion (positional) Latency
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
What are the Pros and Cons?
• 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
Texas Memory Systems, Inc. - The World's Fastest Storage®
What are the Pros and Cons?
• 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
Texas Memory Systems, Inc. - The World's Fastest Storage®
What are the Pros and Cons?
• 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
Texas Memory Systems, Inc. - The World's Fastest Storage®
What are the Pros and Cons?
• 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
Texas Memory Systems, Inc. - The World's Fastest Storage®
What are the Pros and Cons?
• 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
Texas Memory Systems, Inc. - The World's Fastest Storage®
What are the Pros and Cons?
• 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
Texas Memory Systems, Inc. - The World's Fastest Storage®
How About some Numbers?
IOPS Comparison for Various SANs(Source: www.storageperformance.org)
Texas Memory Systems, Inc. - The World's Fastest Storage®
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?
Texas Memory Systems, Inc. - The World's Fastest Storage®
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)
Texas Memory Systems, Inc. - The World's Fastest Storage®
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!
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®
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
Texas Memory Systems, Inc. - The World's Fastest Storage®