Scenario: I wanted to add a new disk to my Centos 6 installation with its own LVM (Logical Volume Manager). The new disk is 25G and is listed as/dev/sdb. It will mounted on the /data directory.
As always please make sure you have everything backed up before attempting this.
Use fdisk -l to get the summary of disks
n (new partition)
p (primary partition)
1 (use first partition)
t (change partition type)
8e (Linux LVM type)
w (write changes)
Next, create the physical volume
Note: pvcreate initializes a physical volume for later user by the LVM. Each physical volume can be a disk partition or a whole disk.
Now I created a new volume group called VolGroupData
vgcreate VolGroupData /dev/sdb1
You can verify all your volume groups on the server by using the vgs command.
Next we will use lvcreate to create a new logical volume (called DataVol in this case) in the volume group we just created.
lvcreate -n DataVol -L+25G /dev/VolGroupData
NOTE: This is did not work as the disk was presented as slightly less than 25G.
To get the exact size (or in my case I just used extents instead)
vgdisplay | grep Free
The extents showed as 6398 so the following command was used
lvcreate -n DataVol -l+6398 /dev/VolGroupData
Once that is complete, we can now go onto formatting the drive
All done. The only remaining task we need to complete is mounting the drive now.
I had already created /data directory (mkdir data from the /)
mount -t ext4 /dev/VolGroupData/DataVol /data
To keep the change persistent edit the /etc/fstab file and add the following line
/dev/VolGroupData/DataVol /data ext4 defaults 1 2
All done. Test by rebooting or just carry on and hope you haven't made a typo!