I have a BTRFS Raid 1, with the following btrfs fi show:    Total devices 4 FS bytes used 1.45TiB    devid    7 size 698.64GiB used 694.15GiB path /dev/bcache32    devid    9 size 931.51GiB used 928.51GiB path /dev/bcache0    devid   10 size 698.64GiB used 694.64GiB path /dev/bcache48    devid   11 size 1.82TiB used 697.00GiB path /dev/bcache16From here, you can see that the three smaller devices are almost full (in fact, they were completely full just a while ago, giving me ENOSPC errors). However, the larger 2TB HDD is mostly empty. The volume is full because any data added to the 2 TB disk must also be mirrored on the other disks, but they're all full. Ideally, I'd be able to move copies from the smaller disks to the 2 TB disk so I'd have room to add more data later.A full btrfs balance seems to juggle the data around but doesn't actually make significant changes to the allocation proportions.How can I fix this?
BTRFS suboptimal multi-disk allocation
btrfs