Mounting single slice from Apple RAID 1

Question

Mounting single slice from Apple RAID 1

Long story short: hardware (enclosure) failure; both drives intact but no way to mount them together. I can, however, load either drive into a SINGLE drive enclosure... and I can see that it should be possible via terminal to create a new mount point (thanks to this thread: http://discussions.apple.com/message.jspa?messageID=9049528), but alas can't QUITE make the leap from the suggestions there to exactly what I need to enter in terminal.

Can someone spell it out just a little more clearly for me? With pictures and or sock puppets?

Thanks.

Posted on Feb 26, 2009 7:38 PM

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Answer 1

Kappy

Level 10

362,007 points

Feb 26, 2009 7:46 PM in response to Sixten C Abbot

Unless I misunderstood the discussion that user had both drives available. You only have one drive available. In a striped RAID only half of everything written to the RAID is written to a single drive with the half written to the other drive. With only one drive accessible you cannot recover anything useful.

If the drives are intact why not just buy another two drive enclosure?

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Answer 2

Feb 26, 2009 7:49 PM in response to Kappy

Thanks Kappy, but we're both talking about RAID 1's which are mirror (RAID 0 are striped).

And honestly, I can't find one (a new dual enclosure) in any of the stores nearby PLUS it's killing me knowing that all the data is there BUT for a little mount point... and I'm feeling cheap.

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Answer 3

Kappy

Level 10

362,007 points

Feb 26, 2009 8:01 PM in response to Sixten C Abbot

If it's a mirrored RAID then just install the drive. The data on each drive is simply a replica. You should be able to install the drive in the enclosure and have it mount normally. Least that's worked for me.

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Answer 4

Feb 27, 2009 6:37 AM in response to Kappy

Not working for me; it doesn't mount and Disk Utility shows it as a RAID slice. Was yours a boot volume? Because that might make a difference.

Apparently (I can't remember if I saw this in that thread or somewhere else) Apple's RAID software splits the mount point between the two drives for some reason that's beyond me (probably because otherwise TWO drives would mount instead of one).

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Answer 5

Kappy

Level 10

362,007 points

Feb 27, 2009 7:25 AM in response to Sixten C Abbot

No, mine was used just as a backup. With a mirrored RAID once the RAID is broken each drive should function just as a single drive. That's the whole point of the mirrored RAID - if a drive goes bad the data are not lost since the other drive is a mirror. My setup uses Disk Utility to create the RAID. It is not a hardware RAID.

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Answer 6

Feb 27, 2009 3:40 PM in response to Kappy

Okay, fair enough -- so, anyone have any ideas why mine wouldn't be behaving the same as kappy's?

How about the fact that my RAID was internal, not external? I don't see why it would make any difference, but I'm just looking for points of differentiation between our scenarios.

Or is there a way to confirm that it WAS a RAID 1 and not a RAID 0? Thanks as always.

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Answer 7

Mar 2, 2009 10:11 AM in response to Sixten C Abbot

Hello?

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Answer 8

terryb

Level 4

3,394 points

Mar 20, 2009 2:29 PM in response to Sixten C Abbot

I'm in the same boat. Two Maxtor 1TB drives striped with Disk Utility as RAID1. One drive had a hardware failure. The other shows as "Failed" in Disk Utility. Running diskutil list shows the drive but I can't get it to mount with "mount -t hfs /dev/<disk> /Volumes/<disk>. The command never returns.

Were you able to figure anything out?

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Answer 9

Mar 25, 2009 4:44 PM in response to terryb

Hey Terry --

no luck for me yet. However, I think that in my case the two drives actually WERE RAID 0, which is why they won't mount individually. But that just leads me to another problem, which I'm going to start as a new question. You may want to try posting yours separately, too. Good luck!

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