How to extend Linux LVM disk

First of all (prerequisite) extend volume on virtualization platform, or add a new disk.

Login to the machine with the extended disk.

To get an overview and find the next partition in the row, do (if sda) the "p"-command in fdisk:

$ fdisk /dev/sda
Command (m for help): p

Disk /dev/sda: 146.1 GB, 146163105792 bytes
255 heads, 63 sectors/track, 17769 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   83  Linux
/dev/sda2              14       17769   142625070   8e  Linux LVM

Stay in the fdisk-interface.

Create new partition, eg. sda3. Partition with Linux LVM fdisk partition ID: 8e.

For new partition do the "n"-command, for new, and then "p" for primary partition:

Command (m for help): n
Command action
l   logical (5 or over)
p   primary partition (1-4)

If eg. sda2 was the last partition of you sda-device, write the next number in the row:

Partition number (1-4): 3

Press enter, and enter again, when choosing first and last cylinder, to dedicate the rest of your disk to the new partition.

The partition should now be created. Time to format it for LVM. Write "t", and choose the partition you just made:

Command (m for help): t
Partition number (1-5): 3

/dev/sda3 has been chosen. Write "8e", which is the format ID for LVM. See a list with "L":

Hex code (type L to list codes): 8e
Changed system type of partition 3 to 8e (Linux LVM)

You are almost done! Everything is saved in memory at the moment. Write the new disk with "w":

Command (m for help): w
The partition table has been altered!

Reboot the machine, or rescan disk. I will just reboot:

$ reboot

When ready... create new physcial volume:

$ pvcreate /dev/sda3

Check if it is OK with pvdisplay:

$ [root@hostname01 ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               vg_hostname01
  PV Size               19.51 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4994
  Free PE               0
  Allocated PE          4994
  PV UUID               3c0kQp-B3NH-htw9-Kq9E-IYXS-ho02-Q0e7pW
  --- Physical volume ---
  PV Name               /dev/sda3
  VG Name               vg_hostname01
  PV Size               80.00 GiB / not usable 2.69 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              20479
  Free PE               0
  Allocated PE          20479
  PV UUID               He2LPw-CGMU-WVYW-QzEd-xnrx-W5Di-HyOEvN

Find name of volume group with vgdisplay:

$ vgdisplay
--- Volume group ---
  VG Name               vg_hostname01

Extend volume group with new LVM partition:

$ vgextend vg_hostname01 /dev/sda3

Find name of Logical volume with lvdisplay + df, of Logical volume you want to extend:

$ [root@hostname01 ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/vg_hostname01/lv_root

$ [root@hostname01 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
                       96G  1.8G   90G   2% /

Extend Logical volume with everything Volume group got:

$ lvextend -l +100%FREE /dev/vg_hostname01/lv_root

Now, resize filesystem, with the resize2fs-command:

$ resize2fs /dev/vg_hostname01/lv_root

Your extended LVM disk should now be ready to use!