RAID5 help

[steford]

Hi guys - slightly urgent this one. Noticed 2 drives failing (in a 4 disk array) at work on Friday AM and contacted Dell who ran their diagnostics and will have an engineer round Monday. However the whole thing fell over Friday at 5:30PM :-(

The Dell Disk Array Manager is showing problems with Disk 1 and Disk 3 in the array. Disk 1 Online (Errors), Disk 3 (Online) but with exclamations against them.

The NAS Volume shows an error as Failed. I've tried reactivating Disk 1 and Disk 3 which works but manually reactivating the volume bombed out after 30% or so regeneration. Volume C (Boot) also show an exclamation but the machine boots OK (this is mirrored across Disk 0 and Disk 1)

Ideally I'd like to have things up and running by Monday - either with a reduced disk set (and await engineer) or by going out and buying disks and rebuilding from tape backup (which I really need to start today as there's around 280GB to recover).

What is the likelihood of repairing this given the current state of things? Anything else I can try? I think my best bet right now is to restore from tape files I know we are working on to another machine and work from that Monday pending engineer. If there is anything I can do to get the thing running though it would be really good.

Thanks so much for any help.

[mbuckhurst]

I suspect the exclamation mark is there to indicate you've got a degraded system, having played about with quite a bit of Dell kit, so long as you've got 3 working drives it should be relatively easy to repair.

Assuming the problem is disk related and not raid controller (which I've had happen in the past). This is what I'd try.

Can you boot the system with the failed drive offline? and see all your data? If the answer is yes, then the system should be recoverable. Sticking in a replacement drive for the failed one and configuring it correctly (I can't help as I haven't configured Dell NAS devices) as a replacement, the raid 5 array should rebuild ok. One way I've done this is to add a new drive as a fail over drive and pull the failed drive, which automatically pulls the new drive into the raid set and rebuilds the array.

If the system isn't stable without the failed drive, then I'd suspect a more serious failure either multiple drive or raid hardware, in which case I'd wait for the engineer to turn up.

mike

[steford]

Thanks mate. All disks do seem to be online - I don't see an option to take offline . Just "reactivate".

[mbuckhurst]

The easiest way to offline a disk is simply to pull it out of the machine, however, make damn sure the failed disk is the one you pull, otherwise you could permamently destroy the array - I tested this once and within 10s of pulling a good disk from a failed array Windows had destroyed itself and was totally unrecoverable.

mike