Error while rebuilding a 2 disk raid 1 array on Dell 1850

I experienced a memory error on my Perc 4 card in my Dell 1850.  I changed the memory (and battery as well) and the machine will now boot.  However, the raid controller reports that one of the two physical drives in my raid 1 array is degraded during the boot process.

I entered the raid configuration utility and attempt to "rebuild" the failed drive, but the rebuild fails around 40% of the way there with a message in the rebuild status bar that says simply "ERROR."

How can I rebuild the failed drive without re initializing the array?
Randy_RAsked:
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rindiCommented:
Replace the bad disk with a good one, then if it doesn't automatically rebuild, assign it as a hot spare, and it should start rebuilding.

There is no point in trying to add a disk that is bad to an array again. Your system is relatively old, so disk failures should be even more expected than ever.
Randy_RAuthor Commented:
So this means the disk is definitely bad?  Is there a way to check that?

Also, if I change the drive, do I need to rebuild the array?

What is the difference between a "hot spare" and a normal disk in a raid 1 array?

Sorry, I'm obviously not an expert.
rindiCommented:
The RAID controller's utility can sometimes give some idea of whether a disk is bad or not, but to properly find out you need to remove the disk and connect to a non RAID controller of another PC, then run the disk manufacturer's diagnostic utility. As far as I know the Perc 4 is a SCSI controller, so it might be a bit hard to find a PC with a SCSI controller to which you could attach the disk.

A hot spare is an extra disk in a RAID array, that isn't being used, but which automatically becomes a member of the array and start syncing should another disk in the array fail.

Of course what I forgot to mention above is to just make an extra full backup before you do anything.
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Randy_RAuthor Commented:
In my case, I'm not sure that would work.  I only have a 2 disk array, so if the hot spare doesn't start syncing until the other disk fails, it will be too late and I will lose my data, no?
rindiCommented:
It doesn't matter. Just replace the bad disk with the new one, then check if it will start syncing automatically. If it doesn't assign it to be a hot spare, and then it should start syncing.
Randy_RAuthor Commented:
Ok, I'll try that.  The replacement disk just needs to be the same size and SCSI, not the same manufacturer right?
rindiCommented:
You should get the disk from Dell, referencing your server model and service tag. You should then get the correct disks. SCSI disks aren't that common anymore, particularly low capacity disks might no longer be available. So you can always get larger capacities. The extra space just won't be accessible (unless of course you also change the other disk).
Randy_RAuthor Commented:
The utililty gives me the model number of the disk and capacity.  I'll look for it.

Thanks Rindi.

I'll write again if I still have problems, so can we keep this issue open?
Randy_RAuthor Commented:
The new drive did the trick.  Thanks!
Randy_RAuthor Commented:
I've requested that this question be closed as follows:

Accepted answer: 0 points for Randy_R's comment #a41041623

for the following reason:

Expert suggestion was to replace drive, which I did.
rindiCommented:
Then you should accept my comment as the solution.

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Randy_RAuthor Commented:
Just as an FYI, I had to rebuild the array without initializing the new disk and then manually rebuild it.
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