There is no single system for backups on Linux. There are many different kinds of archiving programs and formats. You already saw tar, one of the most popular archivers, in Chapter 1. The good news is that there isn't much more to making backups than what you already know; the bad news is that it's not too clear how you should get the archive to the physical medium.
This chapter takes you through the basics of backups: what data you need to back up, what backup devices are available, what types of backups you can make, how to use the most common archivers, and how to use tape drives.
Your backup priorities should be as follows:
Home directories. Try to make daily backups of your home directories.
System-specific configuration and data, such as the stuff in /etc and /var. This should include your machine's list of installed packages.
Locally installed software (for example, /usr/local). You don't want to lose the work you put into custom software installations, so make a backup every now and then.
System software from your distribution. This really is the least of your worries, because you can probably restore this part of the system by reinstalling the operating system. Furthermore, by the time your disk gets around to crashing so hard that you need to restore from backups, you probably want to install a newer version of the operating system anyway.