[ovirt-users] Q: Sparsify/fstrim don't reduce actual disk image size

Hi ! I have VM (under oVirt) with single disk thin provision (~600 GB) running NextCloud on Debian 9. Right now VM HD is almost empty. Unfortunately, it occupies 584 GB (virtual size = 600 GB) All partition (except swap and boot) are EXT4 with discard option. in oVirt “enable discard = on”. # fstrim -av runs successfully: /var: 477.6 GiB (512851144704 bytes) trimmed on /dev/mapper/vg--system-lv4--data /boot: 853.8 MiB (895229952 bytes) trimmed on /dev/mapper/vg--system-lv2--boot /: 88.4 GiB (94888611840 bytes) trimmed on /dev/mapper/vg--system-lv3—sys When fstrim runs again, it trims zero. I even run “Sparsify” in oVirt. Unfortunately, actual size is still 584 GB. Here is /etc/fstab /dev/mapper/vg--system-lv3--sys / ext4 discard,noatime,nodiratime,errors=remount-ro 0 1 /dev/mapper/vg--system-lv2--boot /boot ext2 defaults 0 2 /dev/mapper/vg--system-lv4--data /var ext4 discard,noatime,nodiratime 0 2 /dev/mapper/vg--system-lv1--swap none swap sw 0 0 When disk was partitioned/formatted, swap and boot were created first and positioned at the beginning. What is wrong here? Is it possible to fix all this ? Thanks in advance. Andrei