Hello Everyone,
I am planning the deployment of a new server running RHEL4 u4. The server will have a 2 drive HW Raid1 volume (where i will be installing the OS) and then a 4 drive HW raid5 volume (for my data). I normally don't use logical volume manager but if it actually works as advertised, then it may be beneficial for me to setup the raid 5 volume as an lvm just in case i ever need to expand. I have 2 questions about this:
1) how easy / difficult is it to expand an LVM?
2) are their any backup / restore concerns for using an LVM? I usually use cpio for my linux backups and restores.

any input would help me....thanks in advance.

Newer versions of LVM are easy to expand. It's basically two commands, without having to umount and all that other silly stuff.

cpio will work with LVM. Treat it like it's a normal filesystem. You can also setup LVM snapshots to take backups from.

A nice overview of LVM, includes growing and snapshotting, is here:
http://www.ntlug.org/Articles/LVM