Logical Volume Manager in Linux

• Wikipedia link: http://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux)

Add physical storage to VM

• Launch Oracle VM VirtualBox Manager
• Determine virtual disk file
  server.centos.arunov.fsl -> settings -> Storage -> Controller: SATA -> server.centos.arunov.fsl -> Location
• Open terminal

$ VBoxManage modifyhd “copied-path-of-disk-file” —resize 33280

• Size is in mega bytes
• Note: If attempt to reduce size, error:

VBOX_E_NOT_SUPPORTED
VBoxManage: error: Resize hard disk operation for this format is not implemented yet!

Launch VM

• Launch VM: server.centos.arunov.fsl (hostname: puffin)
• Connect from host terminal

$ ssh root@130.245.126.203

• Login
• List of commands

$ lvm help

• Scan disk

$ lvmdiskscan
 :
/dev/sda2 [ 7.51 GiB] LVM physical volume
/dev/ram3 [ 16.00 MiB] 
/dev/sda3 [ 7.99 GiB]
 :

• See physical disks that are used

$ pvscan
 PV /dev/sda2 VG VolGroup lvm2 [7.51 GiB / 0 free]
 Total: 1 [7.51 GiB] / in use: 1 [7.51 GiB] / in no VG: 0 [0 ]

• /dev/sda3 is not used, create

$ pvcreate /dev/sda3
 Physical volume “/dev/sda3" successfully created

• Add to volume group — find volume group and then extend

$ vgscan
 Reading all physical volumes. This may take a while…
 Found volume group “VolGroup” using metadata type lvm2
$ vgextend VolGroup /dev/sda3
 /etc/lvm/archive/.lvm_puffin_1449_1782662981: write error failed: No space left on device
 Volume group “VolGroup” metadata archive failed.
 Internal error: Attempt to unlock unlocked VG #orphans.

• Turn off VM

Boot from Live CD

• Download live CD CentOS image:
  http://isoredirect.centos.org/centos/6/isos/x86_64/
  For example: CentOS-6.5-x86_64-LiveCD.iso
• Configure VM to have live CD
  server.centos.arunov.fsl -> Settings -> Storage -> Controller: IDE -> empty -> CD/DVD Drive -> Choose a virtual CD/DVD disk file
  Select: CentOS-6.5-x86_64-LiveCD.iso
• Check ‘Live CD/DVD’
• Launch VM
• Boot (text mode)
• Login as ‘root’
• Continue from where we left

$ vgextend VolGroup /dev/sda3
Volume group “VolGroup” succesfully extended

• We’re done with adding storage at volume group and physical volume levels. Next, add to logical volume.

$ lvscan
inactive ‘/dev/VolGroup/lv_root’ [5.54 GiB] inherit
inactive ‘/dev/VolGroup/lv_swap’ [1.97 GiB] inherit
$ lvextend /dev/VolGroup/lv_root /dev/sda3
Extending logical volume lv_root to 13.53 GiB
Logical volume lv_root successfully resized

• Shutdown live CD

$ shutdown -F now

Extend File system

• Remove CD/DVD attachment in VM
• Start VM and login as ‘root’
• Find out mapped device

$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
 5.4G 5.4G 0 100% /

• Resize file system

$ resize2fs /dev/mapper/VolGroup-lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/VolGroup-lv_root is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 3547136 (4k) blocks.
The filesystem on /dev/mapper/VolGroup-lv_root is now 3547136 blocks long.
$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
 14G 5.4G 7.3G 43% /

• Reboot to verify

$ shutdown -Fr now

Open questions

• My disk storage size is 32.5 GB. Retrieved only around 16 GB.
• What is device mapper?
• Could expansion be done without live CD?