{"id":179,"date":"2009-09-13T06:47:00","date_gmt":"2009-09-13T13:47:00","guid":{"rendered":"http:\/\/www.wellys.org\/wellysblog\/?p=179"},"modified":"2009-09-13T06:48:19","modified_gmt":"2009-09-13T13:48:19","slug":"yes-you-can-retain-data-on-a-split-os-x-mirror-raid","status":"publish","type":"post","link":"http:\/\/www.wellys.org\/wellysblog\/?p=179","title":{"rendered":"Yes, you can…(retain data on a split OS X Mirror RAID)"},"content":{"rendered":"

My Leopard installation used a OS X RAID 0 implementation to keep my system safe and sound. I mirrored two 1 TB drives then used them for my startup volume. \u00c2\u00a0When I switched to Snow Leopard, I needed an extra drive to ensure I had sufficient backups prior to installation (I always <\/strong>clean install when I upgrade operating systems.)<\/p>\n

I thought the easiest thing to do would be to “split” the RAID 0 drives up with both containing a complete backup of my Leopard installation. But I also thought it sounded too easy and while purchasing Snow Leopard at the Apple store, I casually asked “can you split a mirrored RAID and retain the data?”<\/p>\n

“No” was the response by two of Apple’s finest.<\/p>\n

Still it seemed worth it to try it. Particularly when Disk Utility actually states (something to the effect) “when deleting a RAID configuration, you’ll end up with two drives containing identical data”. WOW! That is exactly what I want, where do I click?<\/p>\n

Clicking on “Delete”, I waited and voila! \u00c2\u00a0A message informing me that the “Operation can’t be performed because the RAID configuration can’t be unmounted.”<\/p>\n

“Mmmmmm. That should be easy to fix, perhaps Finder is still “using” the drive.” Close all windows, try again.<\/p>\n

“nope.”<\/p>\n

Eject RAID?<\/p>\n

“Nope”<\/p>\n

Reboot? “Nope”<\/p>\n

Use diskutil instead of Disk Utility? “Nope”<\/p>\n

Finally, what if \u00c2\u00a0I booted in SAFE Mode? Ejected the drive, then deleted?<\/p>\n

Bands played in the street, everyone rejoiced, the skies cleared and the sun shone brightly! “It worked!”<\/p>\n

So here’s the deal. To split a Mirrored RAID 0 configuration into two identical drives:<\/p>\n