On a test VM with SLES 12 SP1 with default btrfs setup I ran into a
situation with "no space left on device" on /var/...

As such a default setup will put together the whole installation on
one btrfs filesystem ...


... neither df nor "btrfs filesystem df" will help you hunting the
space hogs, as all share one common pool.

I was able to ease the pressure by removing snapshots that snapper
created automatically:

I would like to ask here if there is a good means to get an overview
where the btrfs file system usage actually comes.

In our case, /var/lib/docker with various docker images appears to be
the culprit, but even there, it seems to be hard to get a realistic
usage information: "du -ksh /var/lib/docker" is reporting far too much
(I think because of the btrfs layering employed by docker), and
"docker images" not enough to justify the usage.

A think a good idea might be relocating /var/lib/docker to a separate
partition out of scope of the btrfs default filesystem?

Thanks for sharing your opinions.

Regards, Tom