reduce and extend logical volume in centos

In this tutorial you are going to learn how to reduce the size of a logical volume and to extend the size of another one.
Scenario: After installing CentOS 6 we got the root directory volume with 50GB size and all the rest space is dedicated to the home directory (240GB), so we are going to show how to increase the root logical volume, and how to reduce the home logical volume.
The steps are:
1. unmount the home directory
2. Check the filesystem
3. resize the actual size of the home directory to be only 40GB.
4. reduce the logical volume
5. extend the root logical volume
6. resize the root partition
4. remount the home directory and check new sizes

Logical Volume Management
LVM management
logical volume manager linux
logical volume manager
logical volume group
logical volume linux
extend logical volume
logical drive
logical partition
lvm linux

resize logical volume