[SOLVED] Remove disk from ZFS pool

[tuxillo]

Hi,

By mistake I added a disk to my pool and now I cannot remove. Is there any way to do so?

root@pve01:~# zpool status
  pool: rpool
 state: ONLINE
  scan: resilvered 0B in 0 days 03:48:05 with 0 errors on Wed Mar 24 23:54:29 2021
config:

        NAME                            STATE     READ WRITE CKSUM
        rpool                           ONLINE       0     0     0
          sda3                          ONLINE       0     0     0
          wwn-0x5000c500b00df01a-part3  ONLINE       0     0     0

When I try to remove the wwn one, I get the following message:

root@pve01:~# zpool remove rpool wwn-0x5000c500b00df01a-part3
cannot remove wwn-0x5000c500b00df01a-part3: root pool can not have removed devices, because GRUB does not understand them

Thanks,

 

[leesteken]

Have you tried zpool detach rpool wwn-0x5000c500b00df01a-part3 instead of remove?
What version of Proxmox and ZFS are you using? Maybe it is possible to evict all data from a vdev with the latests ZFS, I'm not sure about that.
Alternatives are creating a new pool, copy everything and rename it to rpool, which is quite a bit of work, or to reinstall Proxmox and restore from backup.

 

[tuxillo]

Yes, I also tried that and didn't work:

root@pve01:~# zpool detach rpool wwn-0x5000c500b00df01a-part3
cannot detach wwn-0x5000c500b00df01a-part3: only applicable to mirror and replacing vdevs

Proxmox version and zfs versions:

root@pve01:~# zfs version
zfs-0.8.5-pve1
zfs-kmod-0.8.5-pve1
root@pve01:~# pveversion
pve-manager/6.3-3/eee5f901 (running kernel: 5.4.78-2-pve)

 

[tuxillo]

Any ideas?

 

[leesteken]

Are you using GRUB to boot? If so, I don't think you can fix this without creating a new pool, copy everything and rename that pool to rpool, which is quite involved and I would suggest reinstalling Proxmox instead. If you are using systemd-boot, maybe someone known a way to force the removal and ignore the warning about GRUB?
EDIT: If you apt-get update and dist-upgrade your Proxmox, you should get newer ZFS modules (version 2.0.4). Do you still get the same error on zpool remove?

 

[tuxillo]

Yes, I'm using GRUB to boot.

I've upgraded proxmox but I'm afraid to do the 'zpool remove' now. I'll try to backup everything first, then I'll try.

 

[tuxillo]

Eventually I removed the disk from the pool and then, with the remark from @avw, I could attach it as mirror:

  pool: rpool
 state: ONLINE
  scan: scrub repaired 0B in 07:22:19 with 0 errors on Sun Apr 11 07:46:20 2021
remove: Removal of vdev 1 copied 415G in 1h0m, completed on Mon Apr 19 03:12:46 2021
        1.41M memory used for removed device mappings
config:

        NAME          STATE     READ WRITE CKSUM
        rpool         ONLINE       0     0     0
          sda3        ONLINE       0     0     0

For anyone reading this thread later on, the solution is having ZFS modules (version 2.0.4) or newer.

Thanks!

 

[SamTzu]

From the host Shell type:

zfs unmount /sdb
zpool destroy sdb

After that you can use Proxmox GUI to wipe the disk.