I'm trying to recover data from a failed external Fantom RAID Drive enclosure by plugging the drives into a Mac Pro tower, but I'm concerned that OS X might write to the disks and jeopardize the RAID structure.

I believe that the disks are RAID 0, but I am not sure. Also, I am pretty sure that the problem is with the RAID enclosure and not the drives themselves.

How can I mount the drives as read-only to avoid any corruption?

  • Are you aware that you can get write block hardware so that you are 100% sure that the Mac OS won't mount the drive as soon as you plug it in? I'd be wary of spotlight and other indexing processes if the data is very important. – bmike Apr 1 '13 at 22:14
  • I suspect that the drives won't mount as their format will be unknown but I would find out what format they are first – user151019 Apr 1 '13 at 22:52
  • Thanks bmike and Mark. I wasn't aware that you could get hardware write access blocks (unfortunately, acquiring one probably isn't in the budget). – Dan Kwi Apr 2 '13 at 15:33
  • I'm guessing that the drives won't mount either, but if I can give it a relatively risk-free shot (like the Disk Arbitrator Software mentioned by Orangebox below) then it I think it's worth it. – Dan Kwi Apr 2 '13 at 15:42

I use a program called Disk Arbitrator. Its used to block auto-mounts when you connect devices and can also be used to auto mount drives in read-only instead of read.

[Disk Arbitrator windows

(Disk Arbitrator is the green icon, far left)

From my understanding it hops in before the system can mount the drive, and instead mounts as read-only. Probably not as good as using a hardware block, but in most cases its sufficient (and I rely on it for similar purposes)

  • I've tried this tool, v0.5, but it didn't work: I had set it to Mount Read-only and also its "activated" was checked, but when I inserted a drive that's part of a RAID mirror created in a Mac Pro, it did first tell me that the partitions 1 and 3 were rejected (they're EFI and recovery parts, so that's alright), but then it mounted the main volume (partition 2) writable anyway. Now I have a degraded RAID set and have to wait hours for it to re-sync. – Thomas Tempelmann Nov 3 '15 at 15:54

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