Hard Drives No Longer in RAID

illegalprelude · Jun 2, 2013

Hey guys and gals,

Connected to my iMac are two external FireWire hard drives. I had previously set the two as RAID via Disk Utility for Final Cut and have had no problem. Now, after a reboot of the iMac, it seems as if the two have fallen out of RAID. I see both drives in Disk Utility and on my desktop, I only see one hard drive appear yet Disk Utility over all clearly states something different, indicating that one of the drives is missing. Pretty lost on what to do here.

smithrh · Jun 3, 2013

illegalprelude said:
Hey guys and gals,

Connected to my iMac are two external FireWire hard drives. I had previously set the two as RAID via Disk Utility for Final Cut and have had no problem. Now, after a reboot of the iMac, it seems as if the two have fallen out of RAID. I see both drives in Disk Utility and on my desktop, I only see one hard drive appear yet Disk Utility over all clearly states something different, indicating that one of the drives is missing. Pretty lost on what to do here.

Yeah, that's fairly odd.

I was mulling over a couple of scenarios where this might happen, but I dunno. I have quite a few RAID sets, haven't seen this before. Usually what happens to me is that a power supply cable or data cable gets bumped and one of the drives goes offline, then some data gets written to the remaining drive and then they're out of sync and the set needs to be rebuilt.

Options:

* Call Applecare and see if they can figure out what happened.

If you don't have Applecare, I'd try this:

* Power down, turn the "good" drive off (disconnect it) and reboot with the "missing" drive connected (hard to know which one's which, true - note the disk numbers first).

* Try to use the "missing" disk for a while - open some projects, etc.

* Look in Console to see if there are any obvious disk I/O errors for that disk - if so, it's done, toast, etc.

* If you think the "missing" drive is actually OK, you could re-build the RAID set. This will be slow.

* If you think the "missing" drive may have problems, get a replacement drive and then rebuild the set. Also slow.

illegalprelude · Jun 6, 2013

smithrh said:
Yeah, that's fairly odd.

I was mulling over a couple of scenarios where this might happen, but I dunno. I have quite a few RAID sets, haven't seen this before. Usually what happens to me is that a power supply cable or data cable gets bumped and one of the drives goes offline, then some data gets written to the remaining drive and then they're out of sync and the set needs to be rebuilt.

Options:

* Call Applecare and see if they can figure out what happened.

If you don't have Applecare, I'd try this:

* Power down, turn the "good" drive off (disconnect it) and reboot with the "missing" drive connected (hard to know which one's which, true - note the disk numbers first).

* Try to use the "missing" disk for a while - open some projects, etc.

* Look in Console to see if there are any obvious disk I/O errors for that disk - if so, it's done, toast, etc.

* If you think the "missing" drive is actually OK, you could re-build the RAID set. This will be slow.

* If you think the "missing" drive may have problems, get a replacement drive and then rebuild the set. Also slow.

Hey smithrh,

Thank you for the reply. What is the best way to rebuild the raid without losing everything?

smithrh · Jun 6, 2013

You shouldn't lose anything. Been a while since I rebuilt a real, in-service set, but it's there in Disk Utility.

Edited to add: do not expect it to be quick! We're talking potentially an entire day. Set your expectations.

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Hard Drives No Longer in RAID

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