Extend the root file system in Redhat Linux 5.6

Extend the LV(Logical Volume)

root@node ~]# lvextend -L 12g /dev/mapper/rvg-rootlv
  Extending logical volume rootlv to 12.00 GB
  Logical volume rootlv successfully resized
[root@node ~]#

Grow the file system

[root@node ~]# resize4fs -p /dev/mapper/rvg-rootlv
resize4fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/rvg-rootlv is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/mapper/rvg-rootlv to 3145728 (4k) blocks.
The filesystem on /dev/mapper/rvg-rootlv is now 3145728 blocks long.
[root@node ~]#

Check the file system status
[root@node ~]# df -h /
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/rvg-rootlv
                       12G  3.1G  7.6G  29% /
[root@node ~]#