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I have a MacPro with a corestorage LVG, with three physical drives: An SSD and 2 x 2TB drives. The fourth drive in the system was a Time Machine backup disk.

The backup disk and one of the 2TB drives both failed in quick succession. I cannot read any blocks from the two failed disks, tested using a FreeBSD system using SATA and a MegaRAID controller -- the disks don't respond to commands correctly so the issue doesn't seem to be a media issue.

I am assuming the data on these two disks is lost.

Booting from 10.11 USB installation key and running diskutil cs list shows an LVG with a uuid and a offline status. There are three physical volumes listed, the first two are the good devices with a status of "checking", and the third is a UUID and "(No properties)".

Attempting to repair gives "Incomplete or inconsistent CoreStorage Physical Volume set".

Attempting to run diskutil cs removedisk <dead-disk-uuid> gives "Not a valid CoreStorage Physical Volume UUID (-69777)".

The question:

Is a partial recovery of a corestorage LVG with a failed physical disk possible? Is there a way of removing the dead disk from the LVG and getting a (damaged) filesystem view?

  • This is probably no longer an active question for you, but if it is, what was the layout of the Core Storage LVG? Was it a flat striped group with three devices, or were you doing something adventurous with the two 2TB block devices? – incumbent Aug 29 '16 at 15:35
  • @incumbent I have copies of the disk images from the good disks in case some magical technique comes up. No, nothing adventurous with the two 2TB disks, it was a flat striped group. I did try to mirror the 2TB drives when I was setting up the LVG back in 2013 but I couldn't get corestorage to play along. – janm Aug 30 '16 at 1:39

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