How to Shrink or reduce size of LVM partitons in RHEL/CentOS

LVM (Logical Volume Manager) is a tool for logical volume management which includes allocating disks, striping, mirroring and resizing logical volumes.With LVM, a hard drive or set of hard drives is allocated to one or more physical volumes.

LVM allows users to create partitions from more than one disk and allows them to extend the filesystem size online within few seconds.

In this post, we will see how we can shrink the size of an LVM partition without losing data.

On my linux virtual machine, the VG name is “rootvg” and LV name is “Vibhor” which has 60 GB size. I want to reduce the LV size to 4GB. Please note down the following points before proceeding with the shrinking of filesystem.

• Make sure the current disk usage of the filesystem is less than the size to which you are going to reduce the logical volume.

• Always take a backup of filesystem data before doing any size change in LVM as a simple mistake in command can cause filesystem corruption and hence loss of data.

Now, please find the below steps which we need to follow for reduce or shrink the partition size.

Umount the filesystem:

We will check the file system through fsck command but before running fsck on the filesystem, it should be unmounted.You can unmount the filesystem “/vibhor” as follows.

#umount /Vibhor

Performing filesystem check:

Before proceeding with reducing filesystem, “fsck” should be done in order to avoid inconsistency of filesystem data.

#e2fsck –f /dev/mapper/rootvg/rootvg_vibhor

Resizing filesystem:

Now, we will reducing the size of the Logical Volume, but before we need to reduce the filesystem in it. The command “resize2fs” can be used for this as follows.

#resize2fs –p /dev/mapper/rootvg/rootvg_vibhor 4G

This will decrease or shrink the filesystem size to 4GB.

Reducing the LV size:

After reduce or shrink the filesystem, we can reducing the LV as given below.

#lvreduce –L 4G /dev/mapper/rootvg/rootvg_vibhor

This will reduce the logical volume size to 4 GB. Now I will mount the filesystem again and check it using the command “df –h”. the file system has reduced to 4 GB without losing any data.

#mount /Vibhor

#df –h

This output will show you the reduce filesystem size.