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RAID 1+0 to RAID 0?

Estimable Member Customer

I have a mini Thunderbay 4 - 4x 500GB drives that I set up as a 1+0. I tried this as one of the drives is a bit iffy (comes up with will 'die soon') messages but wasn't ready to chuck it out just yet. So I put the good drives as the primary pair and included the 'bad' drive in the mirror. The rationale being that I just replace that bad drive when it did die without compromising the data on the primary pair. So it happened yesterday - the array could not be mounted, so I went to replace the bad drive and add in a new one. However when rebuilding the offsets ran into the hundreds of millions and still at the end, it 'failed' - the process just halted and I couldn't mount the volume. I tried again with another good drive but same again. I thought that I might even mount the two good drives as a volume by themselves but there's no option that I can see.

The data on the volume isn't crucial, it was meant to be a 'scratch' volume of sorts, that's why I chose this method. However I thought I still had a level of convenience built in (see above). I'll just wipe and recertify the drives and build another volume, but I was wondering what causes what I thought was a fairly robust setup to not be able to rebuild/ mount when given a new drive please? 

Topic starter Posted : 22/01/2022 8:46 pm
Member Admin

The problem is you mixed two different assumptions, assuming one covers the other.

A volume is a "container". Everything inside it is controlled by macOS.

The disks that make up the volume are the RAID technology. They only manage the outside of the volume,  they have nothing to do with what is inside.

the fact your volume could not mount, means the volume was damaged, probably the directory.

 Attach a SoftRAID support file. I can take a look. You don't need the disk connected, since you tried to rebuild already, just remove it.

Once the volume can be mounted, then you can replace a disk.

Its like re-caulking a house to prevent water seepage, then your dishwasher leaks . they seem similar, because both are involved with water, but the outer siding cannot prevent a dishwasher leak.

Disk Warrior is the best at repairing a volume directory problem, but it sounds like you have backups, and restoring is easier.


Hope this explanation helps

Posted : 22/01/2022 9:23 pm
Estimable Member Customer

Cheers. Thanks for the explanation. I managed to get just the two primary drives to mount as a volume and copied the data that I wanted off. The rest of just Time Machine files - I have another Then I made up a new volume with good drives.

Topic starter Posted : 22/01/2022 11:36 pm