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I have an 18.04 ubuntu based system using their LVM on top of LUKS setup on one drive, and I want to add an additional drive /dev/sdb to extend root (i.e. /).

VG name lubuntu-vg, LV name root, LV Path /dev/lubuntu-vg/root

I am able to do this as detailed below, but when I boot, the newly crypted drive isn't mounting and I get these errors:

Couldn't find device with uuid 88f32fa1-e533-4b7f-9a3b-f37275766f94.
(snip)
Refusing activation of partial LV lubuntu-vg/root (snip)
/dev/mapper/lubuntu--vg-root does not exist. Dropping to a shell!

The UUID above is for /dev/mapper/sdb1_crypt (not /dev/sdb1). I can boot to a live distrib and manually mount things and access the extended / lvm via cli.

Here's what I'm doing to get to this point:

# Create primary partition n, p, w
fdisk /dev/sdb

cryptsetup -y -v luksFormat /dev/sdb1
cryptsetup luksOpen /dev/sdb1 sdb1_crypt 
pvcreate /dev/mapper/sdb1_crypt
vgextend lubuntu-vg /dev/mapper/sdb1_crypt
lvextend -l +100%FREE /dev/lubuntu-vg/root
resize2fs /dev/lubuntu-vg/root

So far so good now have a large encrypted / using new drive, now set it up to use a key (i've also tried without using a key same issue):

dd if=/dev/urandom of=/root/.keyfile bs=1024 count=4
chmod 0400 /root/.keyfile
cryptsetup luksAddKey /dev/sdb1 /root/.keyfile

Get UUID and add entry to /etc/crypttab:

blkid /dev/sdb1
sdb1_crypt UUID=106b6483-443e-44ec-b134-176db8da927f /root/.keyfile luks,discard

Here's where I'm unsure and maybe going wrong? I'm not adding anything to /etc/fstab because I already have an entry for:

/dev/mapper/lubuntu--vg-root /               ext4    errors=remount-ro 0       1

And then upon reboot the result is the issue detailed at start.

Thanks in advance for help.

Jan Nell
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  • If you change things in your crypttab, you'll likely need to update your initramfs. Also keep in mind that this is happening in your initramfs, where `/root/.keyfile` is unlikely to exist. – Ginnungagap Sep 02 '19 at 22:01
  • Thanks, you were correct changing it to prompt in crypttab and updating initramfs did the trick. Currently I have to enter two passwords but I'm musing options that let me skip this, maybe something involving a yubi key. Good related info here https://wiki.archlinux.org/index.php/Dm-crypt/Device_encryption#Unlocking_the_root_partition_at_boot – Jan Nell Sep 05 '19 at 00:05

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