Hi, I have a mirrored cache pool set up to store my app data. However, now that I have set up CA appdata backup, I am comfortable removing one of these disks from the mirrored pool and using it as a Time Machine backup location instead. I tried clicking on the first drive in the pool and converting to single mode. I stopped the array, attempted to unassign the second drive, but when I tried to restart the array, I received a prompt stating that the pool contained too many missing or wrong devices. Please help!

tower-diagnostics-20250822-1030.zip

18 minutes ago, slam23 said:

I tried clicking on the first drive in the pool and converting to single mode.

You cannot remove a device from a single profile pool; you can from a raid1 pool, so convert it again to raid1 and then you can remove a device. See below for more info:

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/#findComment-480418

I tried converting to raid1 but it didn't seem to work. Seems like my second drive is "missing"?

You cannot convert with a missing device.

How did you start the array after this error?

39 minutes ago, slam23 said:

but when I tried to restart the array, I received a prompt stating that the pool contained too many missing or wrong devices.

Anyway, if all the data is on the remaining device, you should be able to remove the missing one with .

btrfs dev remove missing /mnt/pool_name

This must be done with the array running; after that, reimport the pool:

on main click on the first device for that pool and then "remove pool"

back on main, create a new pool with the same name and 1 slot

assign the pool device, leave the filesystem set to auto

start the array to import the pool

That worked great, thank you so much!