Why you should check out LVM

In this example, we are creating a 130 GB partition and a 16 GB partition.

# lvcreate -n LogVol00 --size 130G VolGroup00
Logical volume "LogVol00" created
# lvcreate -n LogVol01 --size 16G VolGroup00

You would then use the lvdisplay command to examine your logical volumes.

# lvdisplay
  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol00
  VG Name                VolGroup00
  LV UUID                NP2Hzj-M895-y524-ExiG-w7Se-loWj-uwB44q
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                130 GB
  Current LE             4175
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0

  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol01
  VG Name                VolGroup00
  LV UUID                Z3MPGc-4EB8-bFSl-VL3S-huj8-MJ8v-c3FoDK
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                16.00 GB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1

Once you get this far, you're ready to build file systems on your logical volumes. At this point, you will be using familiar commands -- like mkfs and mount.

# mkfs.ext4 /dev/ VolGroup00/LogVol00
# mkdir /apps
# mount /dev/ VolGroup00/LogVol00 /apps

Of course, you have to remember to update your /etc/fstab file with your new file system information.

/dev/VolGroup00/apps      /apps      ext4   noatime   0  2

To enlarge a logical volume, you should unmount it and then use the lvextend command. In the example below, we unmount the file system, check it with the e2fsck command, enlarge it with lvextend then check it again.

# umount /apps
# e2fsck -f /dev/VolGroup00/LogVol00
# lvextend -L+70g /dev/ VolGroup00/LogVol00
Extending logical volume homes to 200 GB
Logical volume homes successfully resized
# e2fsck -f /dev/ VolGroup00/LogVol00

We then need to then run the resize2fs commands to resize the file system to use the space we have just added to the logical volume. We then run e2fsck again for good measure.

# resize2fs -p /dev/VolGroup00/LogVol00
# e2fsck -f /dev/VolGroup00/LogVol00

We can then remount our file system and take a break.

The file system should still be in good shape, just roomier!

There are even more features to LVM than I've mentioned here. A good resource for additional information is:

https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/...