April 20, 2005 at 6:18 am
Does anyone know which disk perfmon counters are valid for SAN disks ?
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
April 21, 2005 at 7:21 am
depends on what type of SAN and whether you have 1:1 mapping between the disks and the luns.
April 21, 2005 at 8:51 am
Your SAN administrator should have software provided by the vendor(s) available for performance monitoring. e.g. EMC, Hitachi and maybe Veritas if you are utilizing the disk management software. The catch is that he willl have to monitor the situation for you.
RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."
April 21, 2005 at 10:53 am
Therein lies my problem - I don't know the internal configuration, it's an EMC SAN, and I'm told it's performing well - I don't agree but I need to be able to provide some sort of evidence to get someone in.
I think my "disks" are shared with other servers, I can at times record very high disk queues but I don't know if there is any relevence to these figures, sigh !!
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
April 21, 2005 at 12:25 pm
Here's a few questions for your SAN admin to start with ...
1) What RAID Level are you using (1,5 or 1+0) ?
>>> The different RAID levels determine optimim read or write performance
2) How many disks per array ?
>>> The more disks the better to distribute I/O. However RAID 5 is a bit slower on writes but excellent for reads.
3) Are you using BCV's (Business Continuance Volumes) ?
>>> This is an EMC SAN thing that allows one to basically make the whole san one big RAID 1 mirror. Then you can take half of it offline to back it up whilst the remaining half of it still processess. When switching reestablishing the BCV's there may be slight performance hiccup on a highy utilized SAN.
4) Are you using LUNS or Meta-LUNs ?
>>> A LUN is a logical slice of space from one disk array.
>>> A Meta-LUN is a logical slice of disk space from many disk arrays. (Meta-LUNs are better in most cases distributing I/O over many disk controllers and disk arrays.
5) What are the disk speeds (7,200/10,000/15,000 rpm).
A SAN can have disk arrays with disks of different speeds (the same peed for each in an array, but different arrays may have fastyer or slower disks). Youd database data and log LUNS should be on the fastest disks there. Wheras backup disk LUNs could go on something as slow as 7,200 rpm spindles.
Well, that's background information. You might also want to check out the EMC sight for whitepapers relating to Windows as well.
RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."
April 22, 2005 at 5:00 am
thanks - appreciated
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
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