I want to change partition sizes / /opt /var
I am not using LVM
HP has a cool Ignite product that allows creation of a tape that can be used to restore the system, changing partition sizes in th process.

Does anybody know a way to do this without re-installing OS?

You probably want to look at the gnuparted utility, or a commercial solution like Partition Magic.

So long as you back up the files in the partition properly (eg. cp -p to preserve all attributes), you can copy the files from the partition to a backup device, delete and recreate the partition, then copy them back.

Beware of using a tape drive for doing this; they are not 100% guarenteed against data loss so you may want to take a second backup just to be sure.

Also, you may need to boot off a live CD (or other rescue system) if you are going to delete your system partitions like /.

If you change the order of partitions, you will need to edit /etc/fstab (and reinstall the bootloader if you move / or /boot).

Thanks rj

What about mondo? Do you know if mondo allows interactive changing of partitioning upon restore?