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Does anyone have experience with changing RAID levels, WHILE IN PRODUCTION, with HP ML350 G6 P410i controller - ESXi 5.1?

Posted on 2014-11-17
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Last Modified: 2015-04-07
I have a ML350 G6 with the "HP Smart Array P410i Controller" and I am considering changing RAID levels: from RAID1+0 to RAID5.

The HP tools are installed on the ESXi server already, and the hpssacli command is verified working per a recent experience with a failed disk.
(also, I understand 1+0 to 5 is potentially stepping back in performance, but the volume I/O is not intense and we feel that we may be better served making use of the additional space)

Present RAID10 volume configuration has 6 disks, 279GB 15K SAS.  Backups of the virtual contents are conducted multiple times a day. Utilization of the volume (containing x2 VMDK files) is about 80% capacity at this time.

I would like to change this 1+0 logical volume to a RAID5 while in production.  Per VMWare's KB and other Expert comments on the Exchange, I'm reading that this is possible so long as there is a BBU and proper HP utils installed, etc.. (which they are).  

As I understand, the command  would be something like (after having verified the proper slot and volume of course):

./opt/hp/hpacucli/bin/hpssacli ctrl slot=0 ld 2 modify raid=5
then
./opt/hp/hpacucli/bin/hpssacli ctrl slot=0 ld 2 size=max forced


Can anyone tell me about their experience(s) on a similar modification?

How long did it take (given your scenario, realize not all configs are the same)?
Does one suggest changing the rebuild priority before starting the modify operation?
How bad, noticeable, was the performance hit during the modification process?
Has this been a failure resulting in data loss (or similar) for any fellow Experts?
Other suggestions, comments are welcome please.

thanks all!
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Question by:ssiremote
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Andrew Hancock (VMware vExpert / EE MVE) earned 500 total points
ID: 40447952
Yes, you will need the BBWC (Battery Backup Write Cache) module installed.

This is a very disk intensive operation, so do not expect it to be quickly, it does take many hours, or days to complete.

and performance is poor, when the RAID is being rebuilt.

Also as this is a disk intensive operation, ensure you have full backups not snapshots, as disks can and do fail, in a rebuild!

How long did it take (given your scenario, realize not all configs are the same)?
Does one suggest changing the rebuild priority before starting the modify operation?
How bad, noticeable, was the performance hit during the modification process?
Has this been a failure resulting in data loss (or similar) for any fellow Experts?
Other suggestions, comments are welcome please.

Yes, to all of the above. We no longer do it, on Production Machines, and we move all the VMs off, to a new Server, and take the old server down!
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