Another question I have regarding upgrades in SLES.
What fail safe “back out” methods are the most common when performing OS upgrades?

In AIX I can use the rootvg unmirror disk concept to quickly boot back to my pre upgrade version in case of problems.

Some of my VM’s are huge so cannot perform snapshot backups. Using rear restore is too drastic and not without its own occasional issues so what “simple” method can I use to guarantee fast fail back when encountering OS upgrade issues??

Thank you