[taken over from stackoverflow since I figured that was probably the wrong place]I am currently testing btrfs as a possible replacement for my NAS running ZFS. I created 4 devices, 20GB each, and created a btrfs filesystem using the balance -dconvert=raid5 option. Then I started to fill the FS using 5GB files (right now I have 9 of them). After creating these files (using dd from dev/zero) I started balance btrfs balance start. After some time it throws the error error during balancing '.' - No space left on device. The syslog brings up this error: btrfs: 4 enospc errors during balance.Running balance again with -dusage=0 completes successfully (as expected) but balance -dusage=90 or simply balance without filters does not work. Why am I caring about this so much? I tested what happens when you remove a harddisk from a raid5 btrfs volume to see if no data corruption takes place. After removing the harddisk I wanted to add another and remove the failed one. This process failed due to enospc errors as well.Additional information below:(the mountpoint for the FS is /mnt/raid/)linux:/mnt/raid # btrfs filesystem showLabel: 'test_raid5'  uuid: 8b137115-974e-4f91-a243-ec6239c34761    Total devices 4 FS bytes used 45.06GiB    devid    4 size 20.00GiB used 16.03GiB path /dev/sde    devid    3 size 20.00GiB used 17.00GiB path /dev/sdd    devid    2 size 20.00GiB used 17.00GiB path /dev/sdc    devid    1 size 20.00GiB used 16.04GiB path /dev/sdbLabel: none  uuid: 69c33622-1c80-4dc3-9c01-24c27def730c    Total devices 1 FS bytes used 1.04GiB    devid    1 size 18.92GiB used 3.04GiB path /dev/sda2linux:/mnt/raid # btrfs filesystem df /mnt/raid/Data, RAID5: total=48.00GiB, used=45.01GiBSystem, RAID1: total=32.00MiB, used=12.00KiBSystem: total=4.00MiB, used=0.00Metadata, RAID1: total=1.00GiB, used=53.69MiBlinux:/mnt/raid # btrfs versionBtrfs v0.20-rc1+20130701linux:/mnt/raid # uname -aLinux linux 3.11.6-4-default #1 SMP Wed Oct 30 18:04:56 UTC 2013 (e6d4a27) x86_64 x86_64 x86_64 GNU/Linuxlinux:/mnt/raid # cat /etc/os-releaseNAME=openSUSEVERSION=13.1 (Bottle)VERSION_ID=13.1PRETTY_NAME=openSUSE 13.1 (Bottle) (x86_64)ID=opensuseANSI_COLOR=0;32CPE_NAME=cpe:/o:opensuse:opensuse:13.1BUG_REPORT_URL=https://bugs.opensuse.orgHOME_URL=https://opensuse.org/ID_LIKE=suseI cannot believe I have to add even more space to this just to be able to rebalance my btrfs volume. Any ideas on this?
btrfs balance fails due to enospc error
opensuse;raid;btrfs