How to unlock LUKS partition at boot?

2026-07-23 16:50 UTC

I have a file system on LVM inside LUKS on a 2nd SSD that I’d like to mount at boot time. The OS boots fine on the main (non-LUKS) SSD. /etc/crypttab contains a line mapping a UUID to a name, with no keyfile. /etc/fstab contains a line mapping /dev/LVMvg/volume to /home/special But I’m not asked for the passphrase at boot. I can do it manually once booted (cryptdisks_start asks for the passphrase, decrypts it, and then LVM picks up the volumes enabling me to mount /home/special.) But I’d like all this to happen early in the boot. How can I make the early processes ask me for the crypt password? Thanks!

Replies (3)

@akunohana@piefed.blahaj.zone 2026-07-23 16:54

Maybe this: https://wiki.archlinux.org/title/Dm-crypt/Encrypting_an_entire_system#LVM_on_LUKS

Open ##4041323
@BillibusMaximus@sh.itjust.works 2026-07-23 17:19

Caveat: I’ve used LUKS quite a bit, but never to do exactly what you’re trying to do, so the following is a guess. If the root disk was the encrypted one, the tooling would add scripts to your initramfs to handle the prompting and unlocking at boot. Since it’s not the root, those scripts maybe not be getting added. I’m not sure about the “right” way to force it to add them, but you should be able to manually tweak your initramfs setup to add them.

Open ##4041904
@moonpiedumplings@programming.dev 2026-07-23 17:47

It looks like KDE and linux mint have the ability to auto unlock and mount drives, according to this bug: bugs.kde.org/show_bug.cgi?id=466731 Probably a feature of the desktop environment.

Open ##4042433