I have six 8TB drives on a BTRFS RAID10 that I installed yesterday on Rockstor (centos 7). df reports the size correctly but space available is 5.7 TiB short of what I expected… what gives?
I did a metadata rebalance while testing, the difference it made was insignificant.
[root@big ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sdf 22T 3.3T 13T 22% /mnt2/main
[root@big ~]# btrfs fi show /dev/sdf
Label: 'main' uuid: 738d116b-ce5d-46cb-8c40-abb4a03b2071
Total devices 6 FS bytes used 3.30TiB
devid 1 size 7.28TiB used 1.10TiB path /dev/sdf
devid 2 size 7.28TiB used 1.10TiB path /dev/sdc
devid 3 size 7.28TiB used 1.10TiB path /dev/sdb
devid 4 size 7.28TiB used 1.10TiB path /dev/sdh
devid 5 size 7.28TiB used 1.10TiB path /dev/sdd
devid 6 size 7.28TiB used 1.10TiB path /dev/sdg
[root@big ~]# btrfs fi df /mnt2/big
Data, RAID10: total=3.30TiB, used=3.30TiB
System, RAID10: total=7.88MiB, used=320.00KiB
Metadata, RAID10: total=6.09GiB, used=3.63GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
According to df -h, if I’ve only used 3.3TiB out of 22TiB, I should have ~18.7TiB Available, but it’s reporting to the entire system that I have 13TiB available… 5.7TiB are missing in action