Is there anything I can do so save my TrueNAS server

TrueNAS General
1

Please help, I backed up some data and didn’t realise I had run out of disk space, and one of my drives had degraded. I rebooted the server, and now I’m unable to access the storage pool because it has gone offline.

root@truenas[~]# zpool import
pool: WBACKUP
id: 18254846807064974669
state: DEGRADED
status: One or more devices were being resilvered.
action: The pool can be imported despite missing or damaged devices. The
fault tolerance of the pool may be compromised if imported.
config:

    WBACKUP                                         DEGRADED
      raidz1-0                                      DEGRADED
        aacd1p2                                     FAULTED Corrupted data
        gptid/obb5f                                 Online
        gptid/96c2                                  Online

root@truenas[~]# gpart show
=> 40 499896240 aacd0 GPT (238G)
40 1024 1 freebsd-boot (512K)
1064 499875840 2 freebsd-zfs (238G)
499876904 19376 - free - (9.5M)

=> 40 3900682160 aacd1 GPT (1.8T)
40 88 - free - (44K)
128 4194304 1 freebsd-swap (2.0G)
4194432 3896487768 2 freebsd-zfs (1.8T)

=> 40 3900682160 aacd2 GPT (1.8T)
40 88 - free - (44K)
128 4194304 1 freebsd-swap (2.0G)
4194432 3896487768 2 freebsd-zfs (1.8T)

2

You can import it (best from the UI) and either copy the data to some other storage or replace the failed drive and resilver.

1 Like
3

Hi, sorry — how can I import the pool? The only option I have under Storage → Pools is Export/Disconnect, and I’m unable to replace the disk because it isn’t showing up in the TrueNAS console. I can only see the two healthy disks.

Thank you

4

Given that you have written that you are on CORE I am stuck looking at screenshots of 13.0 from the official documentation, but in CORE you should have a big blue ADD button in the upper right corner of the Storage → Pools screen.

Like so:

StoragePoolsScreen
StoragePoolsScreen1552×670 111 KB

5

Where did they write that? The disk identifiers certainly don’t look like SCALE but I couldn’t read CORE anywhere explicitly.

6

Bildschirmfoto 2026-01-06 um 14.52.36

@GP24 Click on that “ADD” button, then you are offered the choice of creating a new pool or importing an existing one.

1 Like
7

Lol thanks I was a bit blind there.

8

I used the wrong word, I should have said selected or chosen, not written. :slight_smile:

9

Thank you. I tried that, however, it failed because the pool is not listed in the ‘Select Pool to Import’ menu. I think I may have to rebuild the server, as it looks like the RAID collapsed and the second disk was lost during the resilver on the initial reboot.

10

An emergency import is still possible, as long as there is enough redundancy remaining. The output looks like you have 2 out of 3 disks available in your RAIDZ1.

11

Can you please post the output of sudo zpool import?
Also of interest is the output of: sudo zpool status -v

1 Like
12

…and please post as formatted text (</> button).

1 Like
13

The output for zpool import and status -v are as follows.

root@truenas[~]# zpool import
pool:WBACKUP
id: 18254846807064974669
state: DEGRADED
status: 
One or more devices were being resilvered.action: The pool can be imported despite missing or damaged devices.  Thefault tolerance of the pool may be compromised if imported.config:

    WBACKUP                                         DEGRADED
      raidz1-0                                      DEGRADED
        aacd1p2                                     FAULTED  corrupted data
        gptid/0bb5f07f-9f1b-11ee-af6a-001e67fee6f4  ONLINE
        gptid/96c2e0b5-e11b-11ee-b0cd-001e67fee6f4  ONLINE

root@truenas[~]# zpool status -v
pool: boot-pool
state: ONLINE
scan: scrub repaired 0B in 00:00:12 with 0 errors on Tue Jan 6 03:45:12 2026
config:
Name STATE READ WRITE CKSUM
boot-pool ONLINE 0 0 0
aacd0p2 ONLINE 0 0 0
errors: No known data errors

I can mount WBACKUP pool using zpool import -o readonly=on -f WBACKUP, however, I’m unable to access the shared area because authentication fails.

In read‑only mode the pool status is visible, however, the faulty disk is labeled the same as the online disk. Can I replace the faulty disk to see if it comes back to life and resumes resilvering?

RESILVER
Status: SCANNING
Completed: 00%
Time Remaining:
Errors: 0
Date: 2026-01-02 11:33:38
Name 	      Read 	Write 	Checksum 	Status
/mnt/WBACKUP	0	0		 0          DEGRADED
RAIDZ1	        0	0	     0	        DEGRADED
aacd1	        0	0	     0	        FAULTED
aacd1        	0	0        0	        ONLINE
aacd2        	0	0        0	        ONLINE
14

What if you import with the correct mount point, with or without -o readonly=on?
zpool import -f -R /mnt WBACKUP

15

Hi, it returned the following error.

root@truenas[~]# zpool import -f -R /mnt WBACKUP
cannot import ‘WBACKUP’: permission denied
Destroy and re-create the pool from
a backup source.

16

What if you prefix it with sudo?
sudo zpool import -f -R /mnt WBACKUP