Pre-Upgrade Backup

Before I do an update, I would like to run a program backup such that, if the upgrade fails I can roll back. I’d rather not do an entire server backup.
What folders on the distro box do I need to copy to insure an quick recovery in the event something unexpected happens?
PBX Firmware: 4.211.64-5
PBX Service Pack: 1.0.0.0