Mounting a degraded raid1 partition read-only

Use mdadm examine to extract the offset of the filesystem:

sudo mdadm –examine /dev/shirkahdd/raidroot

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

losetup –find –show –read-only –offset $¹⁾ /dev/shirkahdd/raidroot

• 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