LVM thin doesn't show real values

[5k7]

Hello,

I have a problem with LVM thin configuration especially with free space.
In GUI i have:

LVM thin:


LVM:


It is the same like form pve shell lvs -a form pve directly:


Taking 303 as an exmaple lvs shows that 89% of space is occupied but in fact there is only 50% of occupied space:



It is the same for different containers. Once this values were correct while moving data from original server. Initially I had 20 GB repo and and after unpacking everything it was like it is now - 89% occupied space, but after removing original compressed archive - numbers are still the same.

Probably I'm missing something trivial here

Thanks in advance.

 

[Dunuin]

You could check if your discard isn't working or if there are any snapshots. Both of it could prevent LVM-Thin from freeing up deleted/overwritten data, so your guests filesystems reported size can mismatch the real size it needs on the thin pool.

 

[5k7]

I checked and there is no snapshots

 

[5k7]

Any suggestions ?

 

[fiona]

Hi,
does running pct fstrim 303 help?

 

[5k7]

Thanks it works perfectly. Now it looks like it should:





Can proxmox manage it automatically ? Or this is normal and should be invoked from time to time for example before backup ?

 

[Dunuin]

I've set up a cronjob running a one-liner every hour that trims all LXCs. Can post that later when I"m back home. But be aware that a pct fstrim will lock the LXC causing a backup job to fail. So you need to make sure borh tasks don't eun at the dame time.

 

[Dunuin]

crontab -e

Then add there something like this:

# hourly trim of all LXCs, but not at hours backups might run (skipping 06:00)
0 0-5,7-23 *   *   *   /sbin/pct list | awk '/^[0-9]/ {print $1}' | while read ct; do pct fstrim ${ct}; done >/var/log/cron.log 2>&1

 

[5k7]

Thanks, I will use it