Problems after disconnecting LUKS device
Yesterday I got my 2TB backup disk. I formatted it and then used LUKS to encrypt it and LVM for the Volume Management. After I copied some files to the new disk, I unmounted the disk, unplugged it and ...
... Oh, shit.
I forgot to
cryptsetup luksClose it.
That's not a good thing to do. Always remember to luksClose! It's so much easier
So after reconnecting the device, you can't really decrypt and mount it, because it did not get unmapped (
/dev/mapper/name still exists and so do
No problem, we fix that!
(in the following my mapping name is
extern, change accordingly)
First see current status, especially
Now remove each mapped device (
-media for me, I have 2 partiions on the disk):
dmsetup remove extern-backup dmsetup remove extern-media
Once again check
Open count, it should be
0 now. If so, go on and remove the mapping:
dmsetup remove extern
Now you got rid of all old mappings. Let's try to mount the disk again. Plug it in, then do:
cryptsetup luksOpen /dev/sdb2 extern
Type your password. If the Volume Groups are missing, use:
vgscan vgchange -ay extern
Now you can mount your partitions:
mount /dev/extern/backup /mnt/backup
Once you're done, deactivate the volume groups and close the crypt device:
vgchange -an extern cryptsetup luksClose extern
Now remember to always use these two commands after unmounting the device and use the following to open it:
vgchange -ay extern cryptsetup luksOpen /dev/sdb2 extern
I wrote a little helper script which does exactly these steps as needed. I'll include it in my next post, when I talk about how I use the setup for backups.