On sábado, 16 de abril de 2016 12:05:05 (CEST) Matthias Bodenbinder wrote: > 38# df -h /mnt/test/ > Dateisystem Größe Benutzt Verf. Verw% Eingehängt auf > /dev/sdg 699G 17M 466G 1% /mnt/test
df is not reliable for btrfs raids, it is better to use btrfs fi df to check actual used space. Using btrfs-tools and kernel from sid (4.4): root@mychabol:/mnt/temporal# dd if=/dev/zero of=disk1 bs=1 count=0 seek=750M root@mychabol:/mnt/temporal# dd if=/dev/zero of=disk2 bs=1 count=0 seek=500M root@mychabol:/mnt/temporal# dd if=/dev/zero of=disk3 bs=1 count=0 seek=250M root@mychabol:/mnt/temporal# mkfs.btrfs -f -draid1 -mraid1 disk1 disk2 disk3 btrfs-progs v4.4 See http://btrfs.wiki.kernel.org for more information. Label: (null) UUID: 4fbfda48-3a10-4e1b-92d8-96be759c2a8c Node size: 16384 Sector size: 4096 Filesystem size: 1.46GiB Block group profiles: Data: RAID1 83.00MiB Metadata: RAID1 83.00MiB System: RAID1 12.00MiB SSD detected: no Incompat features: extref, skinny-metadata Number of devices: 3 Devices: ID SIZE PATH 1 750.00MiB disk1 2 500.00MiB disk2 3 250.00MiB disk3 root@mychabol:/mnt/temporal# losetup /dev/loop0 disk1 root@mychabol:/mnt/temporal# losetup /dev/loop1 disk2 root@mychabol:/mnt/temporal# losetup /dev/loop2 disk3 root@mychabol:/mnt/temporal# mkdir test root@mychabol:/mnt/temporal# mount /dev/loop0 test root@mychabol:/mnt/temporal# btrfs fi df test/ Data, RAID1: total=75.00MiB, used=0.00B System, RAID1: total=8.00MiB, used=16.00KiB Metadata, RAID1: total=75.00MiB, used=112.00KiB GlobalReserve, single: total=16.00MiB, used=0.00B root@mychabol:/mnt/temporal# df -h test/ S.ficheros Tamaño Usados Disp Uso% Montado en /dev/loop0 750M 17M 491M 4% /mnt/temporal/test Like in your case, df thinks that there are only 491M usable. However, if I try to fill the volume root@mychabol:/mnt/temporal# cd test/ root@mychabol:/mnt/temporal/test# dd if=/dev/zero of=file.zero dd: escribiendo en 'file.zero': No queda espacio en el dispositivo 1345402+0 registros leídos 1345401+0 registros escritos 688845312 bytes (689 MB, 657 MiB) copied, 3,10508 s, 222 MB/s root@mychabol:/mnt/temporal/test# ls -lh total 657M -rw-r--r-- 1 root root 657M abr 16 13:24 file.zero root@mychabol:/mnt/temporal/test# df -h . S.ficheros Tamaño Usados Disp Uso% Montado en /dev/loop0 750M 674M 64K 100% /mnt/temporal/test With the 75M of metadata, you can check that this fills the three devices. Moreover root@mychabol:/mnt/temporal/test# rm file.zero root@mychabol:/mnt/temporal/test# df -h . S.ficheros Tamaño Usados Disp Uso% Montado en /dev/loop0 750M 17M 657M 3% /mnt/temporal/test Try to do the same to see if df gets more accurate. Still btrfs is quite young, I am not sure if there are serious issues in 3.17, I would make some experiments before actual use. Bests Luis
