Recovering from RAID fail

Ok so I have a server with RAID 5 and the array won't rebuild (1 dead disk replaced but two others with read errors), HP's solution is to replace the disks but of course this means data loss.

The machine is Server 2008r2 running Hyper-V with three VMs.

Of course I have backups but I have managed to copy the VHDs over to an external hard drive. So wondering if there is any problem with the following:

-Replace disks
-Reinstall Hyper-V
-Copy VHDs back to server, attach and start up again.

Thoughts?

If the array won't repair/rebuild then whatever you do you'll have to replace the disks. Once you've done that and got the server running it should be fine to do exactly what you said, assuming the VHDs weren't corrupted during the RAID failure and copy process. Either that, or restore from backup. Which ever is quicker/easier/you're happiest doing. I guess thats the beauty of using VMs - it gives you options!

Personally, I'd probably get the server running, then do a full restore from backup, unless there's a compelling reason to use the copied VHDs instead (which you could always do after the restore).

Sounds about right :)

Will you continue with it in RAID5 or possibly look at RAID6?

Ben

Thanks for the replies.

@plexer: You know I hadn't thought of that until you mentioned it. Well we currently have 4 disks + 1 spare in RAID 5 Array. So we could use RAID 6... just need to get it straight in my head whether this would be better or not...

Quote:

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Originally Posted by sparkeh

So we could use RAID 6... just need to get it straight in my head whether this would be better or not...

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Thinking about it the other errors occurred when trying to rebuild the array using the hot spare. I guess with the double parity of RAID 6 this lessens the chance of a failure during a rebuild.

Yup that would be the most dangerous time for a raid5 array the rebuild because if anything else goes wrong you are screwed.

Did you run regular consitency checks on your array?

Ben

Oh the controller doesn't support RAID 6 anyway.

And no on the consistency checks, not for while. Will do after this though!

One thing you will find a problem with your VHDs is, is that they will need reactivating again. If you've managed to retain the exact MAC address of each VM and input these into each of them as they were before, then it won't be a problem.

I'm assuming you simply copied and pasted the VHDs as opposed to doing something fancy.

@chuckster: Thanks! I hadn't thought about that, the server is still running so I can note these down and make sure they are the same.

I always keep a spare hyper-v host running with nothing on.

When something like this happens I'm hoping its just a case of moving the VHD's over.

You might also want to look at single SSD drives in the future. I've had great success in running a few servers using them. No more mechanical failures :)

Quote:

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Originally Posted by sparkeh

Oh the controller doesn't support RAID 6 anyway.

And no on the consistency checks, not for while. Will do after this though!

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What controller is it?

Ben

Quote:

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Originally Posted by plexer

What controller is it?

Ben

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HP Smart Array... um can't remember the exact model but its an HP ML350 G5.
Also regarding checks, I regularly check the HP Array Diagnostic Utility which I presumed would flag up the errors... hmm but perhaps the drives started having issues during the rebuild...

E200 controller then by the looks of it.

Ben

Quote:

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Originally Posted by plexer

E200 controller then by the looks of it.

Ben

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Yeah just nipped over to the school and it is that one. Won't do RAID 6.

Nope, the P400 with the battery backup module would do though.

Ben