Add extra storage on the fly with LVM2

Currently I am in the process of creating a file/print server for my home network. It's an older computer but I wanted to experiment with various set-ups and configurations. Two of my requirements were that I must be able to add extra storage on the fly and I must be able to see the two hard drives as one logical unit. The only way (at least that I know of) is to use LVM. I have used it in the past, but I never really needed so I usually did not pick it during the install. In fact my current Ubuntu desktop does not have LVM on it.

During my internet searches I came across this great article, A Beginners Guide to LVM. Read this all the way through and you should get a good grasp of the main commands of LVM. Since that article did not really explain how to what I wanted I had to adapt it to my needs. Here are the steps I used to get my 80GB Maxtor(sda) and 60GB Western Digital(sdb) to work together as one logical unit. I am also using ext3 as my filesystem because it supports on-line resizing.

1. Fresh install of Ubuntu Server 8.10
2. Run updates:

   sudo aptitude update && sudo aptitude safe-upgrade

3. Reboot because of kernel upgrade
4. Figure out what the extra hard drive is (mine is sdb):

   sudo fdisk -l

5. Partition the hard drive as Linux LVM:

   sudo fdisk /dev/sdb

6. Initialize partition for use by LVM (on my system sdb1 is swap):

   sudo pvcreate /dev/sdb2

7. Display attributes of volume groups to find your group name (mine is ubuntu-server):

   sudo vgdisplay

8. Add my physical volume to my volume group:

   sudo vgextend ubuntu-server /dev/sdb2

9. Now extend the logical volume root to include the new physical volume:

   sudo lvextend -L128G /dev/ubuntu-server/root

10. Lastly, resize the filesystem to include the new free space:

    sudo resize2fs /dev/ubuntu-server/root

After reading the beginners guide posted above I was able to go through these steps and add extra storage without unmounting the root parition. This is one of the features of ext3, but I do not know whether you can do that with other filesystems. Now I am able to use both drives to the fullest extent and when I want to add another drive it will be quite easy.