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 SQL Server Administration (2012)
 High writelog and pageiolatch waits on new server
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ferrethouse
Constraint Violating Yak Guru

340 Posts

Posted - 04/30/2013 :  21:45:16  Show Profile  Reply with Quote
A few days ago I moved our SQL database to a much more powerful server (has 32 cores and 244 gigs of RAM). Since moving to this server I have seen significantly higher writelog and pageiolatch (ex and up) waits. I know that these both indicate possible IO contention but my physical disk metrics do not show a problem. Read and write latencies average 2 ms/op and 15 ms/op respectively for the data drive and write latencies average 0.5 ms/op on the tlog drive. From what I understand these numbers are very good. Is there a different metric I should be looking at? I'm not noticing any performance problems but will be moving much busier databases to this server soon and want to make sure these waits don't become much worse when I do.

Thanks.

ahmeds08
Aged Yak Warrior

India
573 Posts

Posted - 05/02/2013 :  01:57:19  Show Profile  Send ahmeds08 a Yahoo! Message  Reply with Quote
Is your tempdb on a separate drive and do you have multiple files for tempdb?

mohammad.javeed.ahmed@gmail.com
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ferrethouse
Constraint Violating Yak Guru

340 Posts

Posted - 05/02/2013 :  10:54:53  Show Profile  Reply with Quote
quote:
Originally posted by ahmeds08

Is your tempdb on a separate drive and do you have multiple files for tempdb?

mohammad.javeed.ahmed@gmail.com



Yes and yes.

Last night we moved our tlogs from SAN storage to local DAS storage and the waits appear to be gone :)
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jackv
Flowing Fount of Yak Knowledge

United Kingdom
2004 Posts

Posted - 05/02/2013 :  14:19:08  Show Profile  Visit jackv's Homepage  Reply with Quote
A good tool for for diskIo performance is sqlio - for some generic - outside of SQL Server testing
read details for usage http://www.sqlserver-dba.com/2011/08/disk-io-performance-and-sqlio.html

It is important you do workload and stress testing

Jack Vamvas
--------------------
http://www.sqlserver-dba.com
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chadmat
The Chadinator

USA
1974 Posts

Posted - 05/02/2013 :  14:22:02  Show Profile  Visit chadmat's Homepage  Reply with Quote
quote:
Originally posted by jackv

A good tool for for diskIo performance is sqlio - for some generic - outside of SQL Server testing
read details for usage http://www.sqlserver-dba.com/2011/08/disk-io-performance-and-sqlio.html

It is important you do workload and stress testing

Jack Vamvas
--------------------
http://www.sqlserver-dba.com



This tool is meant for preproduction IO sizing etc..., I wouldn't suggest running it in a production environment.

-Chad
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jackv
Flowing Fount of Yak Knowledge

United Kingdom
2004 Posts

Posted - 05/03/2013 :  02:03:34  Show Profile  Visit jackv's Homepage  Reply with Quote
My recommendation for sqlio is to use it as part of acceptance testing -. It is also useful to compare figures with the server used previously - and could give you some good clues on how to manage the server configuration and disk usage.

for existing production systems, it is also possible to negotiate time outside of business hrs. Many production systems do not have to be available 24 x 7 .



Jack Vamvas
--------------------
http://www.sqlserver-dba.com
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