SQL Server & turning RAID Cache Off 
Author Message
 SQL Server & turning RAID Cache Off

Colin,
  I have seen cases where the RAID controller cache has caused some
performance degredation.  This has to do with the interaction between the
checkpoint process and the controller cache.  The rate at which the
checkpoint process runs is regulated by the speed of writes to your disk
drives.  With a RAID controller cache these writes are very short, on the
order of 1-2 ms.  This causes the checkpoint process to immediately return
and write out more checkpoint data until the number of writes fills up the
controller cache, thus shutting it off.  This can degrade performance.  The
checkpoint process is regulated by the parameter MAX ASYNC IO.
I hope that this helps.
Ed
--
Edward Whalen
President
Performance Tuning Corporation

Phone: (281) 251-3495
Fax:   (281) 376-9987
Pager: (888) 912-3778

Web:   www.perftuning.com



Thu, 02 Nov 2000 03:00:00 GMT
 SQL Server & turning RAID Cache Off

Colin,

 This would usually only occur with a controller with a small amount of
cache, or one where the write-cache can use 100% of the entire cache.  
What controller are you using?

 Try running SQLHDTST.EXE with and without the cache on to see if any
errors are generated.

 Neil Pike MVP/MCSE
 Protech Computing Ltd



Fri, 03 Nov 2000 03:00:00 GMT
 
 [ 5 post ] 

 Relevant Pages 

1. Turning off cache for a single sql-query

2. Caching RAID controllers versus non-cached RAID

3. turn write-to-cache off

4. Turning Off the PTS Cache

5. Performance Testing ( Turn compile cache off ? )

6. Can I turn OFF read cache?

7. Possible to turn off file system cache?

8. Possible to turn off file system cache?

9. Possible to turn off file system cache?

10. Turning cache off on a Seagate drive under AIX - Progress/AIX/Seagate don't mix

11. Long Delay Connecting to SQL Server (MSDE) with Messenger Service Turned Off

12. SQL SERVER - Turning off the IDENTITY Column through code


 
Powered by phpBB® Forum Software