fstrim doesn't run on datastore mounts

[SteveITS]

I noticed on a PBS Hyper-V VM, ext4 disk, trim wasn't running on the datastore drive.

File /usr/lib/systemd/system/fstrim.service has line:

ExecStart=/sbin/fstrim --listed-in /etc/fstab:/proc/self/mountinfo --verbose --quiet-unsupported

/etc/fstab does not contain /mnt/datastore/storename but /proc/self/mountinfo does.

However the fstrim man page shows "The evaluation of the list stops after first non-empty file" which would be fstab.

Logs (journalctl -u fstrim.service) show it's running on /etc/fstab only:

Jan 26 00:46:45 pbs systemd[1]: Starting fstrim.service - Discard unused blocks on filesystems from /etc/fstab...
Jan 26 00:46:45 pbs fstrim[12234]: /boot/efi: 1013.2 MiB (1062432768 bytes) trimmed on /dev/sda2
Jan 26 00:46:45 pbs fstrim[12234]: /: 1.7 GiB (1820901376 bytes) trimmed on /dev/pbs/root
Jan 26 00:46:45 pbs systemd[1]: fstrim.service: Deactivated successfully.
Jan 26 00:46:45 pbs systemd[1]: Finished fstrim.service - Discard unused blocks on filesystems from /etc/fstab.

If one runs fstrim -av manually it runs on the datastore.

Is there a better option than running fstrim on that disk via cron? Is this a configuration bug?

 

[Chris]

Thanks for the report, this is indeed something which is unexpected and needs some additional handling!

I did implement an RFC patch series which would integrate this as scheduled jobs in PBS [0]. For the time being this requires manual setup via either system timers or via dedicated cron jobs.

[0] https://lore.proxmox.com/pbs-devel/20260319143649.681937-1-c.ebner@proxmox.com/T/

 

[SteveITS]

Happy to help. Will watch for it.