Datapool

[FarTooNice]

Hello knowledgeable people,

Over night the main data pool of my NAS running FreeNAS-11.2-U8 on an AMD A10-7850K Radeon R7 + 16GB (non-ECC) system disappeared. It consisted of two striped 10TB HDDs. Initial investigation seemed to show that one of the HDDs was no longer recognized as part of the pool, showing up as "UNKNOWN" in the web-UI.

zpool import main_2x10TB
cannot import 'main_2x10TB': no such pool or dataset
Destroy and re-create the pool from
a backup source.

zpool import
pool: main_2x10TB
id: 3260294990278912054
state: UNAVAIL
status: One or more devices are missing from the system.
action: The pool cannot be imported. Attach the missing
devices and try again.
see: http://illumos.org/msg/ZFS-8000-3C
config:

main_2x10TB UNAVAIL insufficient replicas
gptid/7b2b13f1-8b5f-11e9-8c74-fcaa145de96b.eli ONLINE
2402215082442232617 UNAVAIL cannot open

camcontrol devlist
<ADATA SSD S510 120GB 3.3.2> at scbus1 target 0 lun 0 (pass0,ada0)
<WDC WD100EMAZ-00WJTA0 83.H0A83> at scbus4 target 0 lun 0 (pass1,ada1)
<WDC WD100EMAZ-00WJTA0 83.H0A83> at scbus5 target 0 lun 0 (pass2,ada2)

I figured that I might have a dead drive on my hand and would have to restore from backup. Initial SMART data of all drives suggested no errors or reallocated sectors though. After that I fussed around with different SATA controllers and exchanged all cables, still no available pool.
THEN I restored an older FreeNAS-11.2-U7 config to the system and suddenly the pool reappeared and everything was well again.
I don't know what happened here or how I fixed it, I'd just like it to not happen again. Do any of you have an idea of what might have happened here?

 

[FarTooNice]

I also just realized that I hastily posted the thread without properly completing the title, like an idiot. As I do not seem to be able to edit it I have to ask for your forgiveness.

 

[sretalla]

When ZFS drops a disk like that, you can expect it to happen again if it comes back following a reboot, it's just a question of when you will hit the bad sectors again which trigger the disk to be kicked out.

Running SMART tests now while the disks (including the "bad" one) and checking the results closely will be a good idea. Make sure you have a backup first.

 

[FarTooNice]

When ZFS drops a disk like that, you can expect it to happen again if it comes back following a reboot, it's just a question of when you will hit the bad sectors again which trigger the disk to be kicked out.

Running SMART tests now while the disks (including the "bad" one) and checking the results closely will be a good idea. Make sure you have a backup first.

SMART tests on all drives (both 10TB and the system SSD) didn't yield any issues - I ran them once via FreeNAS with each drive and once with CrystalDiskInfo (running on a Win10 machine with each drive detached and put into a USB dock). I guess I could still run a full sector R/W test on all drives as well but I don't really expect to find the issue there, as multiple reboots didn't change anything. Only after restoring the old config the pool reappeared.