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Marco DV
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‎03-12-2012 07:19 AM - last edited on ‎02-08-2015 09:09 PM by

‎03-12-2012 07:19 AM - last edited on ‎02-08-2015 09:09 PM by

Very slow write speed on MSA20

Hi, I'll try a different approach to a problem I recently talked about here.

 

I have an HP StorageWorks MSA20 array which is connected to a Smart Array 6400 controller inside an HP ProLiant DL380 G4 server.

 

The problem which was noticed, and which I confirmed, is that disk access to the array can be VERY slow.

Based on my tests, read speed is OK, and the problem is only with write operations.

 

e.g.: "hdparm -tT /dev/cciss/c1d0" shows results around 100 MB/s under normal conditions; when doing simple tests instead like "dd if=/dev/zero of=./testfile" I can see that writing starts fast, but begins crawling as soon as the amount of data written reaches 800-900 MB, and then I get terrible transfer speeds between 5 and 20 MB/s.

If I stop the operation, disk activity continues for minutes, slowing down any other disk access.

 

The write cache batteries were old and needed replacement, so they have been replaced now - all four of them, two in the server and two in the array. And they are fully recharged now.

 

Using ACU CLI I enabled the write cache on the MSA20, while I can't enable it on the 6400 controller, which maybe is normal, according to what someone else replied in the other thread, because there is no disk connected directly to it.

 

The installed OS is Fedora Core 5.

All disks in the array are 250 GB models, subdivided into 3 logical drives of around 700 GB each, in RAID 5 configuration.

 

The firmware in the controller should need an update, according to what ACU CLI tells me, but I doubt it can really fix the problem.

 

Also one strange thing is that the ACU graphical interface "crashes" when I select the MSA20, the server instantly reboots. I?m using the latest ACU offline CD I found on the HP web site.

 

Does anyone have anything else to suggest? Any ideas about possible causes for this problem?

Thank you very much.

Marco

 

 

P.S. This thread has been moved from ProLiant Storage Systems to Storage Area Networks (SAN) (Small and Medium Business). - Hp Forum Moderator

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