Detached a disk - oops shouldn't have done that.

[Gob]

I have a jbod external chassis with 24 x Samsung Evo Pro 860 SSD's hooked up to my TrueNas 12.0U3 system
My first Pool (Pool1) is (was) made up of 6 x VDEV mirrors, with two SSD's in each mirror.

It has been running fine for years now apart from the occasional SSD that would report errors every few months. Pulling out the SSD and re-seating it would generally bring it back to life. This would happen on different disks so I just assumed it was a thing I had to live with.

The last time I had an error it was left for a lot longer and when I re-seated the SSD it didn't come back on line. So without thinking I just detached the SSD from within the GUI, thinking I could re-attach it and rebuild that vdev.

When I detached the disk from mirror-1 it seems that vdev disappeared and the one remaining SSD (da4p2) that was in mirror-1 seems to have been absorbed into mirror-0. See zpool status below:

Code:

        NAME                                            STATE     READ WRITE CKSUM
        Pool1                                           ONLINE       0     0     0
          mirror-0                                      ONLINE       0     0     0
            gptid/cadad31c-3de7-11e6-b636-a0369f9adbf8  ONLINE       0     0     0
            da4p2                                       ONLINE       0     0     0
          gptid/cb2dcec4-3de7-11e6-b636-a0369f9adbf8    ONLINE       0     0     0
          mirror-2                                      ONLINE       0     0     0
            gptid/cb81f9c5-3de7-11e6-b636-a0369f9adbf8  ONLINE       0     0     0
            gptid/cbac1df6-3de7-11e6-b636-a0369f9adbf8  ONLINE       0     0     0
          mirror-3                                      ONLINE       0     0     0
            gptid/160225a6-de6d-11e6-bd87-a0369f9adbf8  ONLINE       0     0     0
            gptid/16374c49-de6d-11e6-bd87-a0369f9adbf8  ONLINE       0     0     0
          mirror-4                                      ONLINE       0     0     0
            gptid/f6b692ba-5726-11ea-9ce3-a0369f9adbf8  ONLINE       0     0     0
            gptid/fb2bd574-5726-11ea-9ce3-a0369f9adbf8  ONLINE       0     0     0
          mirror-5                                      ONLINE       0     0     0
            gptid/91a92057-5727-11ea-9ce3-a0369f9adbf8  ONLINE       0     0     0
            gptid/96117264-5727-11ea-9ce3-a0369f9adbf8  ONLINE       0     0     0

So what I would like to know is what has happened to that mirror-1 vdev and the data that was on it? I am not getting any data error so I assume all is kind of still OK.
I now have the spare SSD that was pulled out.
What is the best thing to do? Try and recreate the mirror1 vdev or leave it as it is?

Thanks for any explanation / tips / guidance.

 

[Samuel Tai]

It's not been added to mirror-0. Observe the disk's indent is at the same level as the other mirrors. This means mirror-1, which was a mirror of 2 disks, is now a singleton, so the single disk now stands in the same place as mirror-1.

 

[sretalla]

thinking I could re-attach it and rebuild that vdev.

You can re-attach it.

Under Storage | Pools | Cogwheel for that pool | Status | 3 dots next to the "singleton" (ex-Mirror1 disk) | Extend (then choose your disk to attach).

If that singleton disk fails at any point now, your pool is dead, so I wouldn't wait around.