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darinlmiller
13 Posts
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October 10th, 2007 21:00
Raid 5 array extremely slow
Hello, I am running a Raid5 array with on a Dell PowerVault 220S. It has an internal Perc 4/SC Raid Controller. The writes/reads to this array are at unacceptably low rates. I suspect the issue is because of a cheap controller, or maybe this controller only uses software to handle Raid5 instead of hardware. Any ideas as to what is going on here, and what I can do to improve performance? Thanks for any advice.
darinlmiller
13 Posts
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Posted October 11th, 2007 13:00
Both raid 5 arrays are set with write-through. I am not sure that changing to write-back will make that much of difference. Perhaps I need to upgrade my controller to one with more memory.dining_philosop
60 Posts
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Posted October 12th, 2007 22:00
Make sure your battery is good with write-back.- This might be overkill, but you might try an I/O monitoring tool like this one that helps nail down the root cause of issues like this: http://www.vmware.com/appliances/directory/1084It's on VMware's site, but doesn't just run with VMware.
Dev Mgr
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Posted October 11th, 2007 11:00
Have you checked if your write cache is enabled (set to write-back instead of write-through)?
If you don't have a battery backup on the PERC, this may not be an option (or at least not a good practice) as a loss in power could mean a loss in data.