Mounting a degraded raid1 partition read-only

• Use mdadm examine to extract the offset of the filesystem:

sudo mdadm --examine /dev/shirka_hdd/raid_root

• Use the “data offset” value and multiply it with 512 to create a loopback device:

losetup --find --show --read-only --offset $((2048*512)) /dev/shirka_hdd/raid_root

* If you have to decrypt it remember to use cryptsetup luksOpen now

cryptsetup luksOpen /dev/loop0 shirka-raid-root-unencrypt

• Now mount the partition. To mount an ext4 partition read-only use:

mount -oro,noload /dev/mapper/shirka-raid-root-unencrypt /mnt