Determining Raid Disk Set

Question

Update

Unfortunately looks like the engineer in question had rebuilt the drive we were looking for, and the two sets he thought he had were actually from two completely different machines. I am now going to provide some super high intensity training in the area of "labelling".

Thanks for all the feedback, it was still a valuable learning exercise.

Original Question

There's been much frustration and banging of heads on desks about this, however as embarrassing as it is I'd like to call upon the collective wisdom here to see if there is a simple answer to this problem. I won't go in to detail about how we've ended up in this absolutely stupid situation but suffice to say that everyone is well aware how stupid it is! Unfortunately, i've been tasked with trying to make the best of it.

Ok the current situation is:

• We have FOUR hard drives that are identical.
• They are in RAID 0 pairs.
• Each pair came out of a different machine.
• We DO know which drives belong together, so we have two pairs.

The numpty that took them out neglected to write two important things on the drives:

• Which pair came from which machine.
• Within the pair, which one is disk 0 and which is disk 1.

Following some further unfortunate happenings today we are now in a situation where, to make the best of a pretty nasty situation, I need to get one of those pairs back in to service as it transpires they might be the latest and greatest copy of some important data.

The question therefore is simple:

Is there an easy way to determine, out of each pair, which is 0 and which is 1 - so that I can put each pair in to a machine and see if it is the right one? I have the machine they came out of, and they both came out of identical machines so I expect they will both work ok, however my biggest concern is getting the disks in the right order.

Am I missing something here and might get myself in deeper water?

Other than taking a big stick to the persons involved in this, what are the best opinions and advice snippets that you can offer me to help get those drives resurrected in their original machines?

Within those drives, the server is running Windows Server 2003, and is a Dell 1950. I have other dells including 2950's that I could put the drive(s) in as slaves if there is software that can help identify them. My biggest concern is ensuring no further data loss of course!

Much appreciated.

Matt.

Answer 1

Most decently modern raid controllers won't care what physical slots the drives are in; the RAID config is stored on the drives themselves.

What you'll want to do is to insert one pair into one of the systems, and boot into the RAID config tool with a key combination at boot. If the RAID cards in those Dells are the standard PERC cards, they'll either recognize the pair as belonging to that system (in which case, they'll figure out the geometry right away and it'll be immediately available to boot or mount), or recognize the pair but see that it's from a different system; in this case, it flag the container as "FOREIGN" and refuse to mount or boot to it until you give it your blessing to do so.

As long as you don't let it boot into the OS, or do anything like changing the container config or initializing disks, the data will not be affected.

Answer 2

Were the raids software or do you have a hardware raid controller? If you have a raid controller then depending on your card, you should be able to power the machines on, boot into the raid configuration and check out which order the drives should be based on their serial number.