Knowledge Base

Resizing a live logical volume

If you use lvm to abstract the filesystems away from the direct hardware, you might need to know how to add additional space without taking the filesystem offline. This post shows how you might do that.

Attach new disk

Save current state to a file for comparison.

ls -l /dev/{s,v}d* > ~/ls.dev.sd.before

Install additional disk to system (in hypervisor or attach to physical machine). Scan with rescan-scsi-bus.sh (from sg3_utils package). If that fails, try

find /sys/class/scsi_host/host*/scan | while read line; do echo "- - -" > $line; done
lsblk

Find the name of the new disk:

ls -l /dev/{s,v}d* > ~/ls.dev.sd.after
diff ~/ls.dev.sd.before ~/ls.dev.sd.after

The output should be the name of the new disk.

Create a new partition

How to do it in fdisk:

fdisk /dev/newdisk
n[enter]
p[enter]
1[enter]
[enter]
w[enter]

Add the partition to lvm and the logical volume

pvcreate /dev/newdisk1
vgextend vgname /dev/newdisk1
lvextend /dev/vgname/lvname /dev/newdisk1

Resize the filesystem

Filesystem type ext4 can be resized live:

resize2fs /dev/vgname/lvname