Please help me remo...
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Please help me remove a zombie slice from an APFS JBOD RAID

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In my 5,1 mac pro, I have a Sonnet M.2 4x4 PCIe card with two 2TB nVME SSDs configured as a JBOD concatenated set that I use for storing VST audio libraries. I started running out of space so I just bought and installed a third 2TB nVME drive. After rebooting, OSX (Mojave) asked me to initialize. Rather than formatting the drive first, I used Drive Utility to add it as a slice to the JBOD set directly. After it was done, it reported there was an error. Even though the volume set now reported as 6TB, something didn’t seem right. I wondered if I should have initialized the drive as APFS first prior to adding it to the set so I removed the slice and reformatted it. 

When I tried adding the new drive back into the JBOD set, I noticed that the volume wouldn't mount. Looking at the AppleRAID details, it appears it added the new drive as a slice but never fully removed the previous entry. So, even though I only have three physical drives, the volume thinks I should have four and that one of them is missing or damaged:

  • slice 0: 2TB full
  • slice 1: 2TB almost full
  • slice 2: zombie slice reported as missing/damaged but doesn't really exist
  • slice 3: 2TB completely empty new drive

I have tried physically removing various combinations nVME blades, changing the order they are installed on the Sonnet card, etc. but nothing has allowed the volume to mount so far. Trying to remove any slice via diskutil fails with an error stating that the File System is not Re-sizable.

The most frustrating thing is that all my drives are healthy and I know all my data is there. I haven't added or removed any files from the volume. The ONLY problem is that the JBOD is somehow convinced that there is an extra slice that it can't see. If I knew of a way to make it forget that the extra slice ever existed, I'm sure the drive would be able to mount exactly as before. 

Does anyone have any knowledge on how to fix this?

Here is what diskutil reports:

AppleRAID sets (1 found)


Name:                 PCIe Storage
Unique ID:            78D78E3E-73E0-4F4E-8224-C573B133DA2E
Type:                 Concat
Status:               Offline
Size:                 6.0 TB (6000164831232 Bytes)
Rebuild:              manual
Device Node:          -
#  DevNode   UUID                                  Status     Size
0  disk0s2   AF7AD992-97C8-4A5E-B2C2-0E4AF006D779  Online     2000054943744
1  disk2s2   E39B5659-DDAE-4F76-8D51-0A0C9267CE4E  Online     2000054943744
-  -none-    8A90617A-2EFE-4E8E-8F88-F7E772228FDC  Missing/Damaged
3  disk1s2   26C52D06-A1A3-4462-9DD5-FBD06D74529E  Online     2000054943744


Topic starter Posted : 29/05/2021 3:24 am
Member Admin

This is beyond my humble abilities. Perhaps someone else here knows. You can also try the Apple discussion forums.

If you can't figure it out, perhaps disk Drill can help you recover the files, the trial mode will tell you if it is possible (you implied you are backed up, however)


Might be easiest to start over.

Posted : 29/05/2021 10:24 am
karlfranz liked