September 3, 2011 at 4:58 pm
Hi
we applied sql server 2008 sp2 in our production.
But after we applied it ,we see slowness. we see writelog and log buffer wait types. we checked the disk subsystem, and it looks good. but the ms/write goes up over 300 ms when lot of writes come in and they get clogged. but when there aren't lot of writes, then the ms/write is below 10 ms
we didn't see these writes getting clogged up when we were running the 2008 RTM version.there were some writelog waits, but not as many as now. the end users are facing slowness and freezing
have any one seen behavior like this?
any advice will be of great help
thanks for the help.
September 4, 2011 at 6:09 am
The question is, what is causing it? What are your queries doing and what is your structure such that you're getting excessive writes? Could something have changed between RTM & SP2? Yes. But that's not the place to focus. The place to focus is your code and structure.
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September 4, 2011 at 8:56 am
Microsoft has updated only following stuffs in SP2
SQL Server Utility,
Data-Tier Application (DAC),
as well as integration capability for Microsoft Reporting Services with the Microsoft SharePoint 2010 Technologies
Try applying CUs gfor SP2 in ur DEV environment and measure the performance. Available CUs for SP2 are
CU1
CU2
CU3
CU4
CU5
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September 4, 2011 at 3:21 pm
what version were these databases originally, SQL 2008 or a previous version?
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September 5, 2011 at 4:47 am
so is your storage san, das or internal?
I can't think of anything offhand which might cause this from a SQL service pack, other than there may ( probably will) be changes to the optimiser which would affect queries but that shouldn't affect io issues on the storage.
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September 6, 2011 at 9:57 am
colin.Leversuch-Roberts (9/5/2011)
so is your storage san, das or internal?I can't think of anything offhand which might cause this from a SQL service pack, other than there may ( probably will) be changes to the optimiser which would affect queries but that shouldn't affect io issues on the storage.
it is SAN..
we suspect the SAN and have opened a call with EMC.
we also removed the SP just to confirm that it is not an issue with the SP.
thank you all for the help.
September 11, 2011 at 7:22 pm
What does your disk couters say
Avg Disk secs \Read
Avg Disk secs \Write
Current disk queue length ...
Also did you run a perfmon trace to find the possible resource bottleneck ?
Thank You,
Best Regards,
SQLBuddy
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