Merging multiple RAID volumes on single disk back into one volume

Mister Zippo · March 18

I've got an 8TB drive that was originally part of a 5-disk, RAID-6 array. As such, the drive is appearing as four separate 2TB volumes. I'm trying to merge them back into a single 8TB volume again. Right now I've got the drive plugged into a USB dock.

The problem is that macOS (and Windows) think they're four separate physical disks, not partitions, so I'm not seeing an easy way to delete/merge the volumes in Disk Utility.

I've done this once before, but for the life of me, I can't remember how. I think it was done using Terminal and diskutil. I can also boot into Windows 10 if that makes things easier.

Any help would be appreciated.

cmndr · March 20

Not a direct solution to your problem but are you able to pull all of the data off, format the drive and then slap the data back on?

kokosnh · March 20

As I understand, you don't want to get any data back, just want the HDD erase, and seen as one side, right?
then diskpart with clean, or erase command, or HDD and zeroing is my best bet, but I don't know it it will help.

Or maybe try sending secure erase command?

I remember once a guy has similar problem, but I don't remember the solution (it was years ago).

Mister Zippo · March 23

On 3/20/2024 at 3:29 PM, kokosnh said:

As I understand, you don't want to get any data back, just want the HDD erase, and seen as one side, right?

Yes. There's no data on it that I need to reclaim. I've already erased the four "volumes" as a first step, because I thought I needed to format them all first — I recall that being a step... I think. I'm drawing a blank.