[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
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
linux:/mnt/raid # btrfs filesystem show Label: '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/sdb Label: 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/sda2 linux:/mnt/raid # btrfs filesystem df /mnt/raid/ Data, RAID5: total=48.00GiB, used=45.01GiB System, RAID1: total=32.00MiB, used=12.00KiB System: total=4.00MiB, used=0.00 Metadata, RAID1: total=1.00GiB, used=53.69MiB linux:/mnt/raid # btrfs version Btrfs v0.20-rc1+20130701 linux:/mnt/raid # uname -a Linux linux 3.11.6-4-default #1 SMP Wed Oct 30 18:04:56 UTC 2013 (e6d4a27) x86_64 x86_64 x86_64 GNU/Linux linux:/mnt/raid # cat /etc/os-release NAME=openSUSE VERSION="13.1 (Bottle)" VERSION_ID="13.1" PRETTY_NAME="openSUSE 13.1 (Bottle) (x86_64)" ID=opensuse ANSI_COLOR="0;32" CPE_NAME="cpe:/o:opensuse:opensuse:13.1" BUG_REPORT_URL="https://bugs.opensuse.org" HOME_URL="https://opensuse.org/" ID_LIKE="suse"
I cannot believe I have to add even more space to this just to be able to rebalance my btrfs volume. Any ideas on this?