A level 1 dump will back up all files that have changed since the level 0 dump was last performed, a level 2 dump backs up all files since the last level 1 dump or level 0 dump. Understand Exhibit A on page 188. The dump command has many options. This is the hardest thing to do. Luckily the man pages for dump give you examples for most common drives.
Most backup work is done to some form of magnetic tape media.
As with disks or other media, to use a tape drive under Unix you must have device files defined for that device. Refer back to the notes on adding a scsi device if you have questions aboue this. Most Unix systems will look for an environment variable named TAPE and use that. If not, you will need to know which device you are using. Unix creates multiple device files for the same tape device to handle different types of functions.