[PVE-User] pbs - Nasty atime bug in Ubuntu's kernel-builtin zfs

[Cornelius Hoffmann]

Hi,

I ran in to a very nasty bug with the zfs version included in Ubuntu 
(NOT the pbs default kernel, I'm running PBS in a container), which is 
the base for Proxmox as well as far as I understand it and wanted to 
warn about a problem with access times that is encountered there.

Essentially, this is [1] and it causes the access time update of a 
`touch` command to fail and set it to epoch 0, so Jan 1, 1970. This will 
cause all chunks that should not be pruned to have an extremely old 
atime and thus be pruned, causing a corruption of all backups.

I'm writing here to make sure there is not maybe a kernel update waiting 
with these changes. The newest zfs-linux version in noble has the bug 
fixed as it includes [2], but that change is only visible in the dkms 
module, which I installed to fix this problem in the meantime.

Cc to the pve-user list, if anybody is also running pbs on the normal 
Ubunutu noble kernel on zfs storage.

Best,
Cornelius

[1] https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/2077487

[2] https://github.com/openzfs/zfs/pull/15773

-- 
Cornelius Hoffmann (he/him er/ihm)
#gernperDu