Volume mounted shows different size used

Hi,
Host server has ZFS lxdpool.
I created volume:
lxc storage volume create lxdpool volK1 size=550GB zfs.block_mode=true block.filesystem=btrfs
and the problem is that after uploading files on it shows different used space than on host.

In container:
df -h | grep volK1
/dev/zvol/lxdpool/custom/default_volK1 699G 261G 438G 38% /home/VIRTUALFTP/k1
so 261GB used
On host server:
zfs list -t volume | grep volK1
lxdpool/custom/default_volK1 381G 15.7T 381G -
so 381GB used.

The same situation is with EXT4 filesystem on volume not BTRFS.
What is going on here ?

Due to ZFS compression and snapshots you might want to compare the logicalused size instead of the used size.

Also, note that when you created a volume with size=550GB you are using multiples of 1000 but later on with dh -h you are asking sizes in multiples of 1024.

So when user fullfill (from host point of view) this 550GB - there will be “disk space exceeded” ? Despite inside of container there will be only about 350GB.