Move logical volume to a new physical disk

Question

I have three logical volumes in a single volume group using a single physical volume (the whole existing disk /dev/sda).

I now want to move one of those logical volumes to a new, faster disk, i.e., going from:

/dev/sda |-vg0-root → mounted to / |-vg0-foo → mounted to /foo |-vg0-bar → mounted to /bar

to:

/dev/sda |-vg0-root → mounted to / |-vg0-foo → mounted to /foo /dev/sdb |-vg1-bar → mounted to /bar

From what I understand I cannot use pvmove or vgsplit because there's only one physical volume in the existing volume group.

What's a good approach to achieve this (preferably online, creating a new volume group for the new disk is not a requirement)?

I did check the many similar questions, but as far as I understand, those don't describe my situation. Bonus question: Is using a whole disk as physical volume a bad idea per se? It seems this decision made the solution much harder in my case. — htorque
– htorque, Commented Mar 8, 2015 at 9:15
Do you have any particular reason you don't want to add your new physical disk as a physical volume to the existing volume group? — Ulrich Schwarz
– Ulrich Schwarz, Commented Mar 8, 2015 at 9:26
Not at all. If it makes things easier, the new disk can be part of vg0 as well. — htorque
– htorque, Commented Mar 8, 2015 at 9:31

Jonathan · Accepted Answer · 2024-11-02 17:16:11Z

One volume group solution:

 pvcreate /dev/sdb vgextend vg0 /dev/sdb pvmove -n /dev/vg0/bar /dev/sda /dev/sdb

Be aware the pvmove command can take a long time depending on the size of your disk.

 pvcreate /dev/sdb vgcreate vg1 /dev/sdb lvcreate -l100%FREE vg1 mkfs -t ext4 /dev/vg1/lvol1 mount /dev/vg1/lvol1 /mnt

Now difficult part, all activities MUST stop on /bar:

 cd /mnt ; ( cd /bar ; tar cf - * ) | tar xf - cd / umount /mnt mount /dev/vg1/lvol1 /bar

where

pvcreate erase all data on disk (and prepare for LVM)
lvcreate should create a logical volume lvol1, you specify lv name with -n bar
I use HP-UX syntax for lv, you might have to use /dev/mapper/myvg-mylv syntax

Once you have verified data are OK, in new place:

Wow, seems I completely misread the pvmove man page. In that case I'll obviously settle for the one volume group solution. :) — htorque
– htorque, Commented Mar 8, 2015 at 9:52
Actually, one could use vgsplit after pvmove to achieve the two volume group solution a bit easier (however, the logical volume still needs to be deactivated using lvchange). — htorque
– htorque, Commented Mar 8, 2015 at 12:37
The usefulness of "pvmove" is a very good reason to use a single VG instead of multiple VGs. — tgharold
– tgharold, Commented Jul 5, 2015 at 23:42
It seems like vgreduce can then be used to remove the old volume if that is the requirement (It wasn't for the specific question, but a question asking about moving all volumes would likely be marked a duplicate) — Gert van den Berg
– Gert van den Berg, Commented Nov 15, 2016 at 13:43
warning: tar with * might skip hidden (dot) files. I prefer the following line: tar cC /bar . | tar xC /mnt — Daniel Alder
– Daniel Alder, Commented Dec 22, 2023 at 20:00