Drive Missing from VDEV

[Zain]

Greetings.

I noticed today that one of my drives is missing from one of the vdev's in the pool. I have/had four sets of mirrored disks in the setup (8x4TB drives). The dropped? drive does show up if I attempt to add a vdev, but cannot add it as a mirror - obviously because two drives are required.

zpool status appears to show the same thing:

How do I get this drive back in the mirrored set? Is it as simple as clicking on "extend" under mirror actions for that vdev? I just want to be sure before doing so as I'd like to not cause any further issues.

Debug file available upon request.

TIA,
Zain

 

[Patrick M. Hausen]

In CORE I would write: yes, just click "extend", but I don't know if that works in SCALE and what possibly could have detached the drive from your mirror.

If you want to do it on the command line you can do a zpool attach <pool> <old drive> <new drive>.
"old drive" is the uuid you see in your zpool status output above. "new drive" is the full device path in /dev/diskbygptid or something similar I don't know from memory right now. If you are familiar with Linux, you will find it.

 

[Zain]

I'm not sure why it would have detached but in any case, I clicked on extend and now it is running through the resilvering process. I don't understand why SCALE would say that the array was healthy though...

Looks like it is running quick though...

Oh, well it's done already. So, extend does it.

Thanks!

 

[sretalla]

I don't understand why SCALE would say that the array was healthy though...

Simple...

A pool is healthy when all of its VDEVs have enough replicas to be considered healthy.

If you removed a drive from a mirror, then that (former mirror, now stripe... oddly not showing like zpool shows it in CORE when you do that... still a mirror VDEV) is healthy, having exactly the one copies expected of it.

 

[Zain]

But no alerts? I don’t know when the drive was dropped but jeesh, if the other drive failed I’d have lost data.

 

[Patrick M. Hausen]

If the drive is "correctly" detached, that does not raise an alert. You are free to attach/detach devices to/from a mirror as you see fit. If a mirror drive fails, TrueNAS will raise an alert.

 

[Zain]

Understood, but I did not detach the drive.
I did recently add another mirrored vdev the other day, maybe a bug when adding more drives?

 

[Patrick M. Hausen]

Possibly. With the current BETA state of SCALE I would recommend checking with zpool status every time you do pool operations via UI, after you have finished.

 

[Zain]

Roger that. Thanks.