Hi everyone,
Can anyone help me how can i increase my /root FROM 17G to 50G partition in centos 5.4.
[root@localhost ~]# fdisk -l

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 131 1052226 83 Linux
/dev/sda2 132 2803 21462840 83 Linux
/dev/sda3 2804 3325 4192965 82 Linux swap / Solaris
/dev/sda4 3326 60801 461675970 5 Extended
/dev/sda5 3326 60801 461675938+ 8e Linux LVM
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 20G 2.6G 17G 14% /
/dev/sda1 996M 39M 905M 5% /boot
tmpfs 1009M 0 1009M 0% /dev/shm
[root@localhost ~]#

You might want to think about moving /home, /opt, /usr/local or whatever is using lots of space to a separate partition rather than trying to extend. If you have an open partition (or separate drive), you can do that quickly and easily; you don't want to move /usr but those are good candidates for relocation (and it's a simply entry in /etc/fstab).

[EDIT]
Forgot to include a link to an explanation of how to actually extend using LVM: http://www.linuxhomenetworking.com/w..._Disk_Capacity. Not easy.
[/EDIT]

Hope this helps some.

You can do as tronayne has written, installed new HDD and move most of the folder like /home /var /opt and make change in /etc/fstab or you can install new HDD with LVM and then move the folders so that you don't run out of space in future.