So i have been having this struggle.

I had a m.2 ssd intenso that was having trouble and wanting to replace it with a samsung 970 1tb.
But it was a little bit smaller then the intenso 1tb....

So i tried everything with the help from claude but cant seem to get it working.
I have now a running server with just my one cache drive.

If i add the samsung it will show up als the samsung.

What am i doing wrong?

helder-diagnostics-20260806-1007.zip

Make sure you just add the device and start the array, don't change the filesystem to raid1 or anything else, the pool will be mirrored automatically.

Yes thats what i have been trying to do.
Edit cache, set to 2 devices and add the 970.
But it doesnt do that. I start the array and i get that screenshot i send. It will not be visible.

Then i remove pool and start with the corsair and it is all good again but not with 2 drives.

Reboot to clear the logs, re-add the device to the pool, start the array, then post those diagnostics.

Thank you. I did and here are the diagnostics.

Also added 2 screenshots from my main page with the issue.

helder-diagnostics-20260806-1439.zip

I don't see why it's failing; try reimporting the existing pools and then add the device once more.

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 slots

assign the old pool device, leave the filesystem set to auto

start the array to import the pool

Then stop and try adding it again; if it still fails, post new diags

Thanks again JorgeB helping me with this machine.

Just putting it on Auto was the move.. Tried that couple of tries ago and then i also got the error that it wouldnt find the pool so from that time on i just put the pool in btrfs and it worked with 1. When i added another it just would not work. But i add screenshots it said it would format the 970 and then after i started the array it just works again!
Thank you.