The most difficult part about adding more space to Linux is where to add the space. Ask yourself, where do you want the extra space? /usr, /home, /var? I have seperate partitions for /home, /var, and /usr. Just as an example, I'll use /home and /usr as the mount points for your new drive.
Use the command 'fdisk /dev/hd?' where ? is the new drive to partition. Create two new partitions for what ever size. The use the 'mkfs /dev/hd?1' to create a ext2 filesystem for each of the partitions. (replace the 1 with a 2 for the second). Then mount the new partition under /mnt (for lack of a better place), and copy the existing data there.
mount /dev/hd?1 /mnt
cp -a * /mnt ( is the -a correct? )
That will copy everything in /home to the new partition. Unmount the partition 'umount' and do the same with /usr. Now mv /home to /home.bak (whatever) and mkdir /home. Same for /usr.
modify the /etc/fstab file to mount the new filesystems when the system boots.
/dev/hdb2 /usr ext2 defaults 1 1
/dev/hdb1 /home ext2 defaults 1 1
Since I may have left something out, please go out to http://www.linuxdoc.org
and find a HOW-TO before really doing this.
Easy command huh?
PS. It would be nice to be able to allocate space to any filesystem as needed, as you can on AIX. Less wasted space.