I've got an issue with btrfs free space (not that uncommon), but I was unable to solve it by following most obvious sources. I don't know what I'm missing.
# uname -a Linux archb3 4.6.3-2-ARCH #1 PREEMPT Wed Jun 29 07:15:33 MDT 2016 armv5tel GNU/Linux /home is automounted (no entry in fstab) /home/storage/video /home/cata/files none bind 0 0 # mount | grep btrfs /dev/sda4 on /home type btrfs (rw,relatime,space_cache,subvolid=5,subvol=/) /dev/sda4 on /home/cata/files type btrfs (rw,relatime,space_cache,subvolid=5,subvol=/storage/video) # btrfs fi df /home Data, single: total=1.64TiB, used=1.60TiB System, DUP: total=8.00MiB, used=224.00KiB Metadata, DUP: total=4.00GiB, used=2.16GiB GlobalReserve, single: total=512.00MiB, used=0.00B # btrfs fi show /dev/sda4 Label: 'home' uuid: 1c7e35e8-f013-4f65-9d19-eaa168ac088b Total devices 1 FS bytes used 1.61TiB devid 1 size 1.81TiB used 1.65TiB path /dev/sda4 # btrfs fi usage /home Overall: Device size: 1.81TiB Device allocated: 1.65TiB Device unallocated: 168.93GiB Device missing: 0.00B Used: 1.61TiB Free (estimated): 203.23GiB (min: 118.76GiB) Data ratio: 1.00 Metadata ratio: 2.00 Global reserve: 512.00MiB (used: 0.00B) Data,single: Size:1.64TiB, Used:1.60TiB /dev/sda4 1.64TiB Metadata,DUP: Size:4.00GiB, Used:2.16GiB /dev/sda4 8.00GiB System,DUP: Size:8.00MiB, Used:224.00KiB /dev/sda4 16.00MiB Unallocated: /dev/sda4 168.93GiB
If I get it correctly, there should be no issue with Metadata (over 40% free), and I can't see how there's an issue with Data - 1.64 TiB allocated out of 1.81 TiB available.
I tried to run rebalancing, but it bails out with "no space left of device" message - I remove a directory with ~25 GiB of data, but to no avail.
What am I missing?
EDIT: There are no snapshots on the system, just checked.
EDIT2: I deleted about 50 GB of data and ran defrag - to my amazement, the disk reports now: # btrfs fi df /home Data, single: total=1.71TiB, used=1.70TiB System, DUP: total=8.00MiB, used=224.00KiB Metadata, DUP: total=3.50GiB, used=2.24GiB GlobalReserve, single: total=512.00MiB, used=0.00B
So it's like after removing 50 GB, another 100 GB appeared on the drive.
I want to like btrfs, but it seems utterly unpredictable :/