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RAID volumes not appearing in Disk Utility Storage Devices
I recently had a disk problem where RAID Utility said the disks and volumes were all fine but the volumes were simply absent in Disk Utility. I was at a total loss for what to do, since the system didn't even see any volumes to boot from unless I booted from the install disk, in which case the installer couldn't see any volumes to install on (although it would let me run Disk Utility and RAID Utility). Searching on the web, many people seem to have had a problem like this, but nobody ever came back to report if or how they fixed it.

RAID Utility's apparent total satisfaction with the situation rules out almost any hardware problem -- no need to see if the RAID card somehow got dislodged or anything like that. Even verifying the RAID set (which takes time measured in days -- don't bother) didn't indicate any problems.

In my case, there was a subtle clue from RAID Utility that something was amiss: Each volume was listed as having zero partitions. [crarko adds: I wouldn't call that 'subtle' myself.] The volumes had also been mysteriously renamed (to 'Untitled' and 'R1V1' or something like that), but that didn't seem to affect anything -- the volumes were still the right size.

The correct diagnosis seems to be that the (virtual) RAID disk had gotten corrupted.

Anyway, deleting the RAID set and then recreating it, and the desired volumes, fixed the problem in just a few minutes. From RAID Utility's point of view I was pretty much back where I started, but from the rest of the system's view, the disks were back. Finally there was a volume I could install to. Of course this process loses all the data, but as they say, RAID is not a backup system. If you need to try to rescue your data you could try Disk Warrior, but I didn't try it and don't know if it would work.

[crarko adds: I haven't tested this one. I have seen the Apple RAID Utility say things were fine as an array was in the process of failing, so I don't trust it as a good indicator any more. The hint here is basically something familiar to a lot of us who work with server administration: RAID is not your backup system, and have a recovery plan in case the array goes bad.]
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RAID volumes not appearing in Disk Utility
Authored by: Quixand on Nov 11, '10 03:02:56PM

So What about raid5, does that not protect against disk failure?

And, sorry to be a bit blunt but any monkey capable of creating a RAID array almost certainly knows how to delete and recreate it if it goes pear shaped. I don't see how useful this comment really is?

Some kind of superblock recovery guide using MDADM and a linux live CD might be more helpful?



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RAID volumes not appearing in Disk Utility
Authored by: willdaddy on Nov 14, '10 04:01:40PM
So What about raid5, does that not protect against disk failure?


Multiple disk failure. I've had it happen and it sucks. That RAID you have likely has drives from the same production run and they'll likely have a similar lifetime. Once you've had a drive fail in a RAID 5 and you introduce a new drive, it has to rebuild the new drive from the parity info on the other drives, potentially stressing a drive that doesn't have a whole lot of life in it.

Woe be to you if you don't have a backup or other disaster recovery plan.

While the original poster's solution does seem a bit scorched earth for those of us who like to recover data, it is also a cautionary tale for those who think their RAID is providing backup.

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