RAID 1 with LVM

Convert an existing linear logical volume to a raid1 or mirror

Backgrond

I have a server running on a single disk. I now find myself relying on it more and want redundant storage. The server installer created a single volume group on a single physical volume.

I have added a second disk to the system. I will duplicate the paritioning of the original drive, create a physical volume on it, and convert the existing volume group into a raid1 or mirror across both physical volumes.

Tools

sudo apt install lvm2

Examine disks:

lsblk

Examine physical volumes:

pvscan
pvs
pvdisplay

Examine volume groups:

vgscan
vgs
vgdisplay

Examine logical volumes:

lvscan
lvs
lvdisplay

Prepare the new disk

The new disk is identical in size to the original. Use sfdisk to dump the partition table from the original disk and apply it to the new one. THIS WILL DESTROY ALL THE DATA ON /dev/sdb.

sudo sfdisk --dump /dev/sda > part_table
sudo sfdisk /dev/sdb < part_table

I have two additional partitions (EFI and boot) that I will attempt to manually sync at a later time. For now, create a new lvm physical volume on the new disk.

sudo pvcreate /dev/sdb3

And add it to the existing volume group.

sudo vgextend <vg_name> /dev/sdb3

And finally:

lvconvert --type raid1 --mirrors 1 <vg_name>/<lv_name>