Report: Logical Volume Manager on Ubuntu Feisty (7.04)

Sometimes diskspace is expensive. Isn’t it a pitty to have GB of space left in some partitions, while it is needed in others. LVM brings much more flexibility. You can add new space to a partition any time you need.

Different partitions can be bundled to one “virtual partition” (or more than one) called a volume group. The volume group can now again be separted into different “virtual partitions” called volumes. The advantage is that the volumes can be extended very easily, because they don’t have a fix position. The data is transparently organized over the whole volume group by the LVM. You don’t need to reserve GB of diskspace for each partition for optional use monthes later. You can extend on demand.

The implementation is comparingly easy. At least in my Ubuntu Feisty there is no additional configuration in the /etc branch. I did install the package lvm2 and dependencies.

First enter the admin shell with: “me$ sudo bash“

For the parameters see help:

• “root$ lvm help” shows a list with all the usefull commands.
• “root$ vgcreate help” shows help for vgcreate.
• etc.

Especially useful are the commands ending with …display and …scan to get status informations.

Proceeding:

• Mind to make a backup before.
• Preparing the physical partitions.
• Bundling the pyhsical partions to a volume group.
• Defining logical Volumens in the volume group.
• Formatting logical Volumes.
• Using logical Volumes.

Preparing the physical partitions

• fdisk /dev/sda: create/select partitions and set them to type 8e (Linux LVM)
• pvcreate: Initialize physical volume(s) for use by LVM
  

Bundling the pyhsical partions to a volume group

• vgcreate: Create a volume group
• vgextend: Add more physical volumes to a volume group.

Defining logical Volumens in the volume group

• lvcreate Create a logical volume
• lvresize Resize a logical volume

Formatting logical Volumes

If the LVGroupname is uvg and the LVName is home the dev path is:

/dev/uvg/home

Use the usual formatting procedure to format for ext3 or reiserfs.

Best give labels that equals the name of the logical volume, so home for the LV /dev/uvg/home.

Using logical Volumes

Now you can mount the new volume, copy content to it, enter it to fstab and reeboot. Have as rescue disk available.

Warning: Think twice before putting /, /etc, /boot onto lvm as a beginner. They may be needed to manage the lvm itself. See comments, what to consider. Make a backup first. Then you can try to get all onto lvm.

Related tutorials english:

• http://www.builderau.com.au/program/linux/soa/Set-up-Logical-Volume-Manager-in-Linux/0,339028299,339274722,00.htm
• http://www.howtoforge.com/linux_lvm

Related tutorials german:

• http://www.selflinux.org/selflinux/html/lvm01.html
• http://www.galileocomputing.de/openbook/ubuntu/ubuntu05_004.htm
• http://linuxwiki.de/LVM

Related tutorials french:

• http://doc.ubuntu-fr.org/lvm

Extending the knowlage:

• lvm snapshot