Problem

The following describes the process of resizing a logical volume using an installation of RHEL/CentOS.

Notable

If the XFS file system is used, a volume can be increased, but not decreased, in size.
Decreasing an Ext4 file system can be done offline only, which means that you need to unmount it before you can resize it.
- When resizing a LV with the file system it contains, nothing will happen to the file system, and its data will remain intact.
- Most file system resizing operations can be done online, without any need to unmount the file system.

Solution

Layer 1: Physical Volume (PV)

Create a MBR or GPT partition.
Assign partition to PV.
```
 pvcreate /dev/${DEVICE}
```

Verify the PV.

 # Listing
 pvs

 # Summary
 pvdisplay

 # Hierarchical
 lsblk

Layer 2: Volume Group (VG)

Change the size of the VG.

 # Increase
 vgextend ${VG_NAME} /dev/${DEVICE}

 # Reduce
 vgreduce ${VG_NAME} /dev/${DEVICE}

Verify the VG.
```
# Listing
vgs

# Summary
vgdisplay
```

Layer 3: Logical Volume (LV)

Change the size of the LV.

 # Increase relative size
 lvextend -r -l +50%FREE /dev/${VG_NAME}/${LV_NAME}

 # Decrease absolute size
 lvreduce -r -L -150M /dev/${VG_NAME}/${LV_NAME}

Verify the LV.

 # Listing
 lvs

 # Summary
 lvdisplay

 # Filesystem
 df -h

Create a file system on top of the LV.
```
 mkfs.xfs /dev/${VG_NAME}/${LV_NAME}
```

Summary

The main part of LVM flexibility resides in how easy it is to resize a VG and LV backed by a PV.