Step by Step guide: Resizing File System on the Linux Virtual Machine

Assumptions made:
You must have basic knowledge of LVM to follow the instruction.
Linux Environment : I have done this on SLES 11; However the LVM commands used are the generic Linux commands. Thus, this instruction should work on wide flavors of Linux.
Volume Group (VG) name: testvg
Logical Volume(LV) name: testlv
Root file system is on /dev/testvg/testlv file system  and I want to increase the file system size by 5 GB.


Step1: Provision an extra disk space to the Virtual Machine [ i.e Increase the VMDK size of the VM via vSphere client if you are on VMWare environment]

[Note: If you provision an additional disk (some VMs doesn't allow to increase the VMDK size), check if you can see that additional disk. Say an additional disk is /dev/sdb. Then, run the command  #fdisk -l   . It should show  /dev/sdb. If you cannot see /dev/sdb, then reboot the system and run #fdisk -l  command again]

Step2: Partition the additional disk space you just added [ Say your system sees disk as /dev/sda ]
           # fdisk   /dev/sda

• Create a new partition (primary if possible) Let's say  /dev/sda4
• Define size
• Change the partition type from 83 (EXT3) to 8e (LVM)
• Write the change

Step3: Create a Physical Volume 
            # pvcreate <partition_name>

                    Example: # pvcreate  /dev/sda4

If you get an error reporting that system can't see the partition, reboot the Virtual Machine.
And re-run the pvcreate command once the system is back up. 

Note: You can run #vgdisplay command to check what Volume Groups are available

Step4: Extend the Volume Group [ i.e Add the physical volume we just created to the existing volume group]

           # vgextend    <vgname>   <partition_name>

                 Example: # vgextend   testvg   /dev/sda4

Note: You can run #lvdisplay command to check what logical volumes  are available
Step5: Extend the Logical Volume  [ Say increase by 5GB ]
           #lvextend   -L     +5G    /dev/<vgname>/<lvname>   <partition_name>

                   Example: #lvextend   -L   +5G   /dev/testvg/testlv     /dev/sda4

Warning!!! Check if a space is free in the physical volume or not. You can run the command #pvdisplay  and check how much free space is available in the physical partition. 

Step6: Resize the file system
          #resize2fs     /dev/<vgname>/<lvname>

                Example: #resize2fs    /dev/testvg/testlv

Note: If resizze2fs doesn't work, reboot the system. For example: SLES 10 doesn't support online resize of the mounted file-system. Thus, SLES10 requires reboot after 'lvextend' of root file-system. 

Validate if the size of the file system has been increased or not. 

         #df  -h

Best of Luck!