I'm a fan of System Restore on Windows XP. It can save you in a pinch and unlike a full backup you . I was wondering if there's an equivalent program available for Linux. Any help? Also is there a freeware System Restore like program for Windows? I could write a system restore like program however I can't match the speed of a system restore. I was wondering how does snapshot software work?

System restore basically just stores a copy of your system files in a second location and undoes those changes if needed. I do something similar with rsync: just make an image of my current system settings.

You can get just about the same results with backing up the /etc directory, as that holds the settings for 99% of the programs that have an effect on the system as a whole. Backing up the hidden files in your home directory (the ones starting with a .), will take care of the user settings.

A number of the snapshot programs work by keeping an image of the changes to the hard drive (or parts of it), and then the restore just rolls back the changes.

There are some differences. System Restore (from what I gathered), keeps backups of the system at states. Not only does it backup config files (like the registry), but it also keeps state on system files and programs installed (this is why by default it eats up to 12% of the drive). The system restore process is closer to svn or cvs as in how it works. Rather than back up the entire system every time it only updates files that were modified since the last snapshot. It uses the older snapshots for the other files in case o restore. This gives you the same effect as a backup but eats up a lot less space. Like cvs/svn it keeps backups of all files for as long as it keeps records of them.