[SOLVED] VM backup size a lot larger than VM used space

[Rayures]

Hi there,

something is going on, that i do not yet understand.

i am backuping a VM (zstd). this gives me a backup file of 46GB. This is a lot, because the VM only has about 11GB in use.

on VM:

df -lhT

Filesystem     Type      Size  Used Avail Use% Mounted on
udev           devtmpfs  2.9G     0  2.9G   0% /dev
tmpfs          tmpfs     597M  8.6M  588M   2% /run
/dev/sda1      ext4      121G  5.6G  109G   5% /
tmpfs          tmpfs     3.0G     0  3.0G   0% /dev/shm
tmpfs          tmpfs     5.0M     0  5.0M   0% /run/lock
tmpfs          tmpfs     3.0G     0  3.0G   0% /sys/fs/cgroup
tmpfs          tmpfs     355M     0  355M   0% /run/user/1000

so, about 11GB in use.

when i look on the pve host at the vm disk:

zfs list -o space

NAME                   AVAIL   USED  USEDSNAP  USEDDS  USEDREFRESERV  USEDCHILD
ZFSdata/vm-188-disk-0   290G  92.0G        0B   92.0G             0B         0B

that is 92GB....

why is de VM disk 92GB when the VM only has 11GB in use? What is going on here? How to reduce this?


//edit

for some reason it looks like debian did not do TRIM automatically (discard is enabled in vm). I ran it manually in the VM:

sudo /sbin/fstrim --all || true

result:

NAME                    USED  AVAIL     REFER  MOUNTPOINT
ZFSdata/vm-188-disk-0  6.89G   376G     6.89G  -