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FAST, Pools and SQL I/O Contention
Hi All -
We have a CX4-480 (4.30), FAST enabled with 1 general pool that consists of SATA, FC and SSD drives. I have a DBA telling me that his SQL 2008 R2 db is stating it is running into i/o contention on a specific drive. We have our SQL data and log's separated on different LUNs. When I run Analyzer on the drive the DBA is telling me SQL is having challenges with, Analyzer does not find any major i/o contention. Has anyone else been unable to actually match up reported SQL i/o contention with SAN LUN contention and if so... what did you end up doing to fix it, if anything?
Maybe I am not looking at the right stats. I am looking at Read and Write IO/s Throughput, can some suggest other stats that may be more useful? Thanks!
dynamox
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September 11th, 2012 09:00
did you run perfmon on that drive and see what's he is talking about ?
AnkitMehta
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September 11th, 2012 10:00
I happen to know just a right person who would be best to answer this, I have already notified him and with time permitting he would respond this!
kelleg
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September 11th, 2012 11:00
It may have to do with having the logs and data in the same pool - in SQL the IO profile for Logs is different from the IO profile for Data. Logs are more small, random writes - usually best on R10 and data are more reads, better on raid 5. The old practices using regular raid groups and separating logs from data in different raid groups with Logs using R10 and data using R5 (can't remember what Temp files used - maybe R10 also).
Also, FAST Cache night not be best for the Logs - if you have the Log LUNs in a separate Pool you could enable FAST cache for the other Pool and not the Log Pool.
glen
AnkitMehta
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September 11th, 2012 11:00
Thanks a ton glen