I have had a 4 disk zfs cache setup for a while and I encourntered an issue with a cable on one disk. The cable is now fixed, the cache re-silvered but the unraid UI lists a blue square next to the disk ('new device'):

Fix common problem plugin reports the disk is 'disabled':

The pool status appears to be okay (it has been running like this for a couple of weeks without issue)

I have tried stopping/starting the array to see if it would rebuild the disk. Even tried stopping, unallocating disk, starting, stopping, re-allocating disk and starting the array again. Everything is working fine except for what is reported in the Unraid UI or fix common problems plugin.

Any ideas on how to rectify?

Full diagnostics attached in case it helps.

vault-diagnostics-20250613-1416.zip

Reimporting the pool should resolve that:

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 number of slots

assign the pool devices, leave the filesystem set to auto

start the array to import the pool

Thanks - that appears to have worked.

I run into the same issue. Somhow my brand new Samsung 990 Pro failed (i guess maybe a thermal issue). After rebooting it looks good again. But it shows blue "New" device.

Is the suggested fix really save and the official way?!? It feels wrong to have to remove the array! I don't want to mess things up, that's my app settings drive.

Yes, reimporting the pool is the best way to resolve that.

Scary but seems to work. How is the raid being rebuilt? Is this visible somewhere?

1 hour ago, Tscherno said:

How is the raid being rebuilt?

Nothing is rebuilt by doing that, the pool is just reimported, that is to be done when the pool is OK, just the GUI status doesn't match.

But how could this be - the one drive was offline for quite a time.

It may not the same issue as this thread; if the device was not assigned to the pool, start by posting the diagnostics with the array started.