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cornall
Posting Yak Master
148 Posts |
 Posted - 2007-06-08 : 09:02:55
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| In perfmon for a particular SQL server I am getting an average disk queue length of over 400 thousand! I have read that a value over 2 is bad. Another server running the same application has a value of 0.005! Has anyone seen anything like this before?!?! |
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cornall
Posting Yak Master
148 Posts |
Posted - 2007-06-08 : 09:31:20
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| it just hit 10 million!!!! |
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Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)
7020 Posts |
Posted - 2007-06-08 : 09:34:29
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| That doesn't even sound possible.CODO ERGO SUM |
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cornall
Posting Yak Master
148 Posts |
Posted - 2007-06-08 : 09:55:04
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| The database is on a SAN I am now reading these counters may not be acurate for a SAN? |
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bpgupta
Yak Posting Veteran
75 Posts |
Posted - 2007-06-08 : 09:58:23
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| You should put this counter for monitor for atleat 1 day and find out the average of all the values . |
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cornall
Posting Yak Master
148 Posts |
Posted - 2007-06-08 : 10:04:47
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eyechart
Master Smack Fu Yak Hacker
3575 Posts |
Posted - 2007-06-08 : 10:21:53
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| i never monitor average disk queue length, just current disk queue length. make sure you select this counter for all your drives.-ec |
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cornall
Posting Yak Master
148 Posts |
Posted - 2007-06-08 : 11:11:54
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| So I shouldn't worry about the strange values above? |
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eyechart
Master Smack Fu Yak Hacker
3575 Posts |
Posted - 2007-06-08 : 11:32:24
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quote:
Originally posted by cornall
So I shouldn't worry about the strange values above?
i didn't mean that :)I think the average queue length is misleading. Current disk queue length is a better counter imho. Create a counter log and monitor it for several hours to see what the trend is. Make sure you monitor all drive letters in your system btw. If the value is still high, then you need to investigate why your disks are so busy and see if that can be remedied (expensive queries, bad indexes, etc.). If you cannot fix that, you will want to make changes to your disk subsystem so it can support more disk IOs (add spindles, upgrade RAID controller, change to RAID 10, etc.)-ec |
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cornall
Posting Yak Master
148 Posts |
Posted - 2007-06-08 : 12:26:07
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| Cheers I will run long term monitoring on the io counters. I am also planning to run SQLIO and SQLIOStress to test the SAN make sure it is getting decent IO performance compared to the same DB running on a SCSI raid config. |
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rmiao
Master Smack Fu Yak Hacker
7266 Posts |
Posted - 2007-06-08 : 13:12:07
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| Can also let SAN guys monitor channel utilization. |
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eyechart
Master Smack Fu Yak Hacker
3575 Posts |
Posted - 2007-06-08 : 14:19:05
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quote:
Originally posted by cornall
Cheers I will run long term monitoring on the io counters. I am also planning to run SQLIO and SQLIOStress to test the SAN make sure it is getting decent IO performance compared to the same DB running on a SCSI raid config.
What SAN vendor are you using? What HBA? What switch? It is also important to check HBA firmware, fiber switch firmware, HBA drivers and such. -ec |
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cornall
Posting Yak Master
148 Posts |
Posted - 2007-06-11 : 05:34:25
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| I don't know which SAN at the moment. I am working for an application vendor our application is performing poorly. I suspect it is the disk set up but have to be politicaly sensative about what I say! need to run some monitoring and tests before I can start accussing their SAN! |
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eyechart
Master Smack Fu Yak Hacker
3575 Posts |
Posted - 2007-06-11 : 11:44:15
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quote:
Originally posted by cornall
I don't know which SAN at the moment. I am working for an application vendor our application is performing poorly. I suspect it is the disk set up but have to be politicaly sensative about what I say! need to run some monitoring and tests before I can start accussing their SAN!
I would just ask the hardware guys if you are downlevel on hba/switch firmware and drivers. Pretty simple question - and if they get bent out of shape about that question then they are officially whiney bitches. In that case it is legal and appropriate for you to kick sand in their faces and steal their lunch money.-ec |
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Perfmon Avg. Disk Queue Length