I used to have RAID10 btrfs setup with 4 disks. Now I added sdf a new disk (its doing the balancing):
Total devices 5 FS bytes used 5.73TiB devid 1 size 3.64TiB used 2.78TiB path /dev/sdd devid 2 size 3.64TiB used 2.78TiB path /dev/sdc devid 3 size 3.64TiB used 2.78TiB path /dev/sdb devid 4 size 3.64TiB used 2.78TiB path /dev/sde devid 5 size 3.64TiB used 336.00GiB path /dev/sdf
What I don't understand is that how is disk 5 inserted into this array?
By looking at the standard raid10 I would say it got into as a 3rd mirror to the right on the picture (storing the A2 A4 A6 blocks) but I'm sure it's done differently for BTRFS.
Could someone explain it please?