If you have LUKS partitions on gpt-partitioned drives, you might have noticed that cryptsetup doesn’t handle PARTUUID=[…] entries in /etc/crypttab, even though it does understand the traditional UUID=[…]. There’s an Ubuntu bug for this (since 2010, because that’s how much Ubuntu cares about bug reports), and apparently Arch is patching cryptsetup to make it work.
But it turns out there’s an elegant workround for everyone, as inspired by this Debian mailing list post, where a user has /dev/disk/by-id/[…] entries in their /etc/crypttab. /dev/disk is just the most delightful symlink squaredance! If you don’t know about it yet, just ls -lR /dev/disk and prepare to be amazed 🙂
So, to make cryptsetup correctly parse the gpt partuuid of your drives, just use /dev/disk/by-partuuid/[…] symlinks in /etc/crypttab. Here’s an example of such a setup:
root UUID=00000000-[…]-444444444444 none luks backup0 /dev/disk/by-partuuid/55555555-[…]-999999999999 none luks backup1 /dev/disk/by-partuuid/aaaaaaaa-[…]-eeeeeeeeeeee none luks