I am trying to recover a disk that has corrupted superblock but I cant seem to unmount the disk at all. I used bcache for the three extra drive after a reboot one of the drive stopped working. so I removed the SSD cache drive and still cant seem to recover the drive
pavs@VAS:~$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 149.1G 0 disk
├─sda1 8:1 0 133.4G 0 part /
├─sda2 8:2 0 1K 0 part
└─sda5 8:5 0 15.7G 0 part [SWAP]
sdb 8:16 0 2.7T 0 disk
└─sdb1 8:17 0 2.7T 0 part
└─bcache0 251:0 0 2.7T 0 disk /var/www/html/directlink/FTP1
sdc 8:32 0 1.8T 0 disk
└─sdc1 8:33 0 1.8T 0 part
└─bcache1 251:1 0 1.8T 0 disk
sdd 8:48 0 1.8T 0 disk
└─sdd1 8:49 0 1.8T 0 part
└─bcache2 251:2 0 1.8T 0 disk
pavs@VAS:~$ sudo fsck.ext4 -v /dev/sdd1
e2fsck 1.42.9 (4-Feb-2014)
/dev/sdd1 is in use.
e2fsck: Cannot continue, aborting.
pavs@VAS:~$ umount -l /dev/sdd
umount: /dev/sdd is not mounted (according to mtab)
pavs@VAS:~$ umount -l /dev/sdd1
umount: /dev/sdd1 is not mounted (according to mtab)
1072.806897] EXT4-fs (bcache2): ext4_check_descriptors: Checksum for group 640 failed (57199!=0)
[ 1072.806900] EXT4-fs (bcache2): group descriptors corrupted!
