What directories should be added to BackUp Linux Mint 18?

Question

Backup

Good afternoon, the other day there was an unpleasantness with updating Mint, I fixed the trouble, but I thought about Backup. The question is what directories should be copied before using the Update Manager? Having studied the file system, I realized that I should copy the following directories:
1.home
2. etc
3.usr
For example, if there was a Linux kernel update and some things stopped working, will these backups somehow help to roll back to the previous working version?

Answer 1

In general, everything is important only in home. In case of a kernel upgrade, it's best not to remove the old kernel for a couple of weeks, so that in case of any problems you can boot with the old kernel.