Here's how I do it. I have two 80 GB drives. Each is partitioned
identically with three partitions:
1. 64 MB Used for raid1, makes md0, JFS, /boot
since grub can't read LVMs
2. 16 GB Used for raid1, makes md1. This one block
device is the physical volume for volume group 'system'.
Since I put the current backup in /var/local (see below), size this
to hold the debian system plus the size of your backup
set, unless you're using streaming tape or other
direct-to-off-the-box backup setup.
3. remainder (64 GB), each used for PVs for volume group
'local'.
VG 'system' is broken up into LVs:
root 300 MB, JFS, mounted on /
usr 4 GB, JFS, /usr
var 6 GB, JFS, /var
swap 1 GB. Yes swap is on LV on raid1.
/tmp is on tmpfs
This way, one drive failure doesn't cause the system to crash since even
swap is protected by raid1.
VG 'local' right now only has one LV:
home 12 GB, JFS, /home.
This is just straight LVM, I can add a drive (PV) to VG
local and extend /home anytime.
When I get into video editing, I'll likely create a stripped LV and
mount it somewhere, make it sticky like /tmp so user's can use it.