Extending a LVM Volume (e.g. /opt) in Cenots 7

What Does LVM Mean?

Taking a description from The Geek Diary:

The Logical Volume Manager (LVM) introduces an extra layer between the physical disks and the file system allowing file systems to:

  • Be resized and moved easily and online without requiring a system-wide outage.
  • Use discontinuous space on disk.
  • Have meaningful names to volumes, rather than the usual cryptic device names.
  • Span multiple physical disks.

Extending a LVM Volume (e.g. /opt):

Run “vgs” to display information on the available volume groups. This will tell you if you have “free” space that you can allocate to one of the existing logical volumes. In our case, we have 30 GB free.

$> vgs
  VG     #PV #LV #SN Attr   VSize   VFree
  rootvg   1   7   0 wz--n- <63.00g <30.00g

Run “lvs” to display the logical volumes on your system and their sizes. Find the one you want to extend.

$> lvs
  LV     VG     Attr       LSize
  homelv rootvg -wi-ao----  1.00g
  optlv  rootvg -wi-ao----  2.00g
  rootlv rootvg -wi-ao----  8.00g
  swaplv rootvg -wi-ao----  2.00g
  tmplv  rootvg -wi-ao----  2.00g
  usrlv  rootvg -wi-ao---- 10.00g
  varlv  rootvg -wi-ao----  8.00g

Extend the logical volume using “lvextend”. In our case, I’m moving /opt from 2g to 5g.

$> lvextend -L 5g rootvg/optlv

Display the logical volumes again if you like. You won’t see a change yet, it will still say 2.00g.

Use df -hT to show what kind of file system you are using for the volume you resized. This can change the next command you have to do.

$> df -hT
Filesystem                Type      ...
/dev/mapper/rootvg-rootlv ext4      ...
devtmpfs                  devtmpfs  ...
tmpfs                     tmpfs     ...
tmpfs                     tmpfs     ...
tmpfs                     tmpfs     ...
/dev/mapper/rootvg-usrlv  ext4      ...
/dev/sda1                 ext4      ...
/dev/mapper/rootvg-optlv  ext4      ...
/dev/mapper/rootvg-tmplv  ext4      ...
/dev/mapper/rootvg-varlv  ext4      ...
/dev/mapper/rootvg-homelv ext4      ...
/dev/sdb1                 ext4      ...
tmpfs                     tmpfs     ...

If it is ext4, you can use the following command to tell the system to recognize the extended volume. If it is not, you will have to find the appropriate command for the given file system.

$> resize2fs /dev/mapper/rootvg-optlv

Now you should see the extended volume size in “lvs” or “df -h”; and you’re done!

$> df -h
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/rootvg-rootlv  7.8G   76M  7.3G   2% /
devtmpfs                   3.9G     0  3.9G   0% /dev
tmpfs                      3.9G  4.0K  3.9G   1% /dev/shm
tmpfs                      3.9G  130M  3.8G   4% /run
tmpfs                      3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/mapper/rootvg-usrlv   9.8G  2.6G  6.7G  29% /usr
/dev/sda1                  976M  119M  790M  14% /boot
/dev/mapper/rootvg-optlv   4.9G  1.9G  2.9G  40% /opt
/dev/mapper/rootvg-tmplv   2.0G   11M  1.8G   1% /tmp
/dev/mapper/rootvg-varlv   7.8G  3.2G  4.2G  44% /var
/dev/mapper/rootvg-homelv  976M   49M  861M   6% /home
/dev/sdb1                   16G   45M   15G   1% /mnt/resource
tmpfs                      797M     0  797M   0% /run/user/1000

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