Logical Volume Manager (LVM) is used in Linux to abstract the filesystems away from the physical disk they sit on.
Volumes can be grown online BUT cannot be reduced online. In order to reduce a volume group, the volume must be unmounted. For volumes containing the root file system, you need to boot using a live boot CD. Once the live CD is loaded, you can activate the Volume Groups by typing:
vgchange -a y
Check file system
e2fsck -f /dev/vgNAME/lvNAME
Extend the logical volume. For example, to increase the file system from 15G to 20G:
lvextend -L +5 /dev/vgNAME/lvNAME
ext3 file systems can be grown on-line.
ext2online -v /dev/vgNAME/lvNAME
Others file systems will need to resized while the file system is unmounted.
resize2fs -p /dev/vgNAME/lvNAME
Check file system
e2fsck -f /dev/vgNAME/lvNAME
REDUCE THE FILESYSTEM FIRST
If you reduce the size of the logical volume without first reducing the size of the file system, reduction will not work, since the file system will be incorrect after the volume is reduced.
Check file system
e2fsck -f /dev/vgNAME/lvNAME
Resize the file system. For example, resize the file system from 20G to 15G.
resize2fs -p /dev/vgNAME/lvNAME 15G
Reduce the size of the logical Volume, in our example 20G to 15G is 5GB difference.
lvreduce -L -5G /dev/vgNAME/lvNAME
Check file system again
e2fsck -f /dev/vgNAME/lvNAME
fdisk new disk and create primary partition of entire disk and set the partition type to be linux LVM (8e). Add partition to LVM.
pvcreate /dev/cciss/c1d2p1
Either create a new Volume group
vgcreate vgNEWNAME /dev/cciss/c1d2p1
or extend an existing Volume Group
vgextend vgNAME /dev/cciss/c1d2p1
Then, either create a new logical volume
lvcreate -L 120G -n lvNEWNAME vgNAME
or use the “Grow Volume” to resize a logical volume to use the new drive.