Eu tive uma raid 5 matriz de 3 discos usando btrfs (raid fornecida por btrfs ) um dos discos foi danificado e eu substituí o disco via:
btrfs device add /dev/sdc /media/raid/
btrfs device delete missing /media/raid/
que forçou um reequilíbrio entre os discos, após o qual o FS estava bem.
Uma reinicialização posterior:
[11152.188020] BTRFS info (device sdb): enabling auto defrag
[11152.188028] BTRFS info (device sdb): disk space caching is enabled
[11152.189762] BTRFS: failed to read chunk tree on sdb
[11152.196224] BTRFS: open_ctree failed
pc ~ # mount -a
mount: wrong fs type, bad option, bad superblock on /dev/sde,
missing codepage or helper program, or other error
Em alguns casos, informações úteis são encontradas em syslog - try
dmesg | tail ou mais.
O sistema operacional começou comentando essa linha em fstab , mas eu descomentei essa linha depois.
LABEL="raid" /media/raid btrfs compress=lzo,noatime,autodefrag
Estou usando o Gentoo Linux, kernel 4.0.5.
Veja btrfs fi show:
Label: 'raid' uuid: 906ed4e3-52c5-4eb7-bd06-4810c0b84902
Total devices 3 FS bytes used 775.29GiB
devid 1 size 931.51GiB used 390.06GiB path /dev/sdb
devid 3 size 931.51GiB used 390.04GiB path /dev/sde
devid 4 size 931.51GiB used 390.03GiB path /dev/sdc
pc / # btrfs-find-root /dev/sdc
Superblock thinks the generation is 1758
Superblock thinks the level is 0
Found tree root at 30818304 gen 1758 level 0
Well block 30457856(gen: 1757 level: 0) seems good, but generation/level doesn't match, want gen: 1758 level: 0
Well block 29753344(gen: 1590 level: 0) seems good, but generation/level doesn't match, want gen: 1758 level: 0
Well block 29507584(gen: 1589 level: 0) seems good, but generation/level doesn't match, want gen: 1758 level: 0
Well block 4243456(gen: 3 level: 0) seems good, but generation/level doesn't match, want gen: 1758 level: 0
Well block 4194304(gen: 2 level: 0) seems good, but generation/level doesn't match, want gen: 1758 level: 0
Você tentou montar o volume com a opção recovery ?
De man mount :
recovery : Enable autorecovery attempts if a bad tree root is found at mount time. Currently this scans a list of several previous tree roots and tries to use the first readable.
mount -o recovery /dev/sdb /media/raid
Tags btrfs