March 2, 2004 at 8:58 am
I'm currently running SQL Server, clustered on a SAN. It's all good. My thoughts are that we should have multiple LUN's for the SAN to prevent possible queueing and to improve performance, exactly as you would for a standard RAID array. Trouble is that my manager is not convinced that having multiple as opposed to single LUNs will actually improve performance. I have not been able to find anything to backup my theory on this, does anyone know of any links or articles so I can defend my position?
March 2, 2004 at 8:52 pm
Sample case from MS.
http://www.microsoft.com/sql/techinfo/administration/2000/rosetta.asp
March 2, 2004 at 10:16 pm
Actually, we've experienced issues with not having the database files not spread out over enough LUNs. Our managers were convinced that since the EMC does RAID 10, that a single large volume would be sufficient for our use, however after experiencing numerous errors (such as "scheduler 0 appears to be hung") MS recommended we move to multiple LUNs.
The number of LUNs you should use depends entirely upon the number of concurrent I/O requests to the SAN. MS recommended we move the heavier volume database files onto a separate LUN and continue to monitor the I/O queue. They recommended that if the queue exceeded 10,000 that further splitting should be done. (It should be noted that the errors we were encountering only occurred when the queue reached approx. 25,000 I/Os and happened very rarely but it resulted in a non-responsive server for 3-5 minutes each time it occurred.)
No two environments are identical nor are any two database usage patterns. I'd definitely recommend at least two LUNs, data file(s) on one and the log file(s) on the other. Use a third if you're utilizing log shipping and/or database backups to disk.
David R Buckingham, MCDBA,MCSA,MCP
March 3, 2004 at 5:13 am
Thanks, just the kind of thing that I was looking for.
Viewing 4 posts - 1 through 3 (of 3 total)
You must be logged in to reply to this topic. Login to reply