RHCSA Logical Volume Manager

The benefits of using LVM

1. Create Extremely large logical volumes
2. Add logical volumes in a running system
3. Add hard disks to volume group in running system
4. The snapshot feature allows consistent backups in a running system

Create a physical volume

The first step in LVM is to start with a physical partition. Create a partition using fdisk or parted. Assume that partition is /dev/sda1. To set up a new PV on a properly configured partition, apply pvcreate command:

#pvcreate /dev/sda1

If more than one partition configured as a PV:

#pvcreate /dev/sda1 /dev/sda2 /dev/sdb1

Create a volume group:

#vgcreate MyVol0 /dev/sda1  /dev/sda2

To include additional PV or to extend a VG:

#vgextend MyVol0 /dev/sdb1

Create a logical volume:

#lvcreate  -L 3G MyVol0  -n home

Use of Logical Volume:

Create a mount point and mount LV home to mount point.

#mkdir /Test

#mount /dev/MyVol0/home /Test

Remove a LV:

#umount /dev/MyVol0/home

#lvremove /dev/ MyVol0/home

Resize Logical Volumes:

Backup existing data on LV mounted directory for example /home and unmount it.

First extend the VG, if it doesn’t have more space.

#vgextend MyVol0 /dev/sdc1

#vgdisplay MyVol0          - to view total of VG

Then extend LV

#lvextend  -L 200M /dev/MyVol0/home

Then resize the LV with resize2fs

#resize2fs /dev/MyVol0/home

Or to use just a part of LV,