I've never done this before so it seems like right now would be a
great time to learn. Thanks in advance.

I've just done this installation on my laptop. For the most part it's
working fine. Still a few things to iron out but it's good enough that
I'd like to save the state of the machine so that should something
happen I have a way to restore where I am today. Since the disk usage
is currently about 4GB it seems like a great time to do it. Is this
possible? I think it's essentially what the stage 3 file is that I use
when I install, isn't it? If I can keep the whole thing under 5GB then
I can write it on a DVD and I'm in a really safe space for a fast
reinstall if something happens.

From the running system here's what things look like right now:

laptop1 ~ # df
Filesystem       1K-blocks    Used Available Use% Mounted on
/dev/sda5         15820524  3641240 11375636 25% /
udev              10240     172   10068  2% /dev
/dev/sda6         1320272   189304  1063900 16% /var
/dev/sda7         10278304   312012  9444184  4% /home
shm             1003844      0  1003844  0% /dev/shm
laptop1 ~ #

My thought is to boot using the install CD, mount a USB drive at
/mnt/gentoo, then create a mount point 'backup' on the USB drive to
mount each of the 3 partitions I want to back up one at a time. ( /,
/var and /home) Then I'll mount each partition by itself and use tar
to create a single file for each partition where that file gets
written on the USB drive. When I'm done I have 3 files.

Restore would be to create the partitions anew, untar, install grub
from in the chroot, and reboot.

Is this a reasonable way to go? Is there something easier? (That seems
pretty easy to me...)

I don't want to create images of the partitions because I might want
to put the data onto a different drive or in a different
configuration. (Like no /var or something.)

If this makes sense then what commands would I want to use to do this
correctly. Presumably it needs to tar up links, file system
permissions, and everything else. Since the Quick Install guide uses

tar xjpf stage3*

to extract the main directories & files, and assuming the USB drive is
sdb1, would I just use

mount /dev/sdb1 /mnt/gentoo
mount /dev/sda5 /mnt/gentoo/backup
tar cjfp ./ROOT.tar.bz2 backup

and then repeat for the other two partitions? Or is there more to it?

I'm rambling here so I'll hope for a quick answer and then give it a try.

Thanks in advance,
Mark
--
gentoo-user@(protected)