So, here's my setup. I have one partition with the newest version installed, a second partition with an older version installed (as a backup just in case), a swap partition that both share, and a boot partition so the bootloader doesn't need to be setup after each upgrade.
- sda1 ext3 /boot
- sda2 ext4 / (current version)
- sda3 ext4 / (old version)
- sda4 swap /swap
- sda5 ntfs (contains folders symbolically linked to /home on /)
So far it has been a very good setup. I can modify the boot loaders for new installs without messing with the MBR. Adding my personal files (from the /home partition) is as easy as creating some symlinks in my home folder (even on a Windows install).
Here's the issue. I'd like to be able to deploy an installation in the 'current version' partition to overwrite the 'old version' partition effectively making it the new 'current version'.
The goal here is to do the install with no USB drives, external hard drives, or CD copies.