RAB is a small backup system intended to be used on a single home PC. RAB will save all data on mountable media carrying an ordinary filesystem. Consequently, you don't have to worry about tapes and inconvenient data retrival, but have direct access to your precious files. By the way, RAB is supposed to mean Random Access Backup.
RAB is used to backup your user data, but not the base operating system. This should be on a CD anyway. We don't provide any sophisticated methods to restore your data, this simply isn't necessary since all backups are on normal block devices which can be mounted.
We distinguish two different kinds of directories to be backed up. The first type is a directory containing files which change frequently, for example a directory under /home where you are doing your programming, or your CVS tree. The second directory type is an archive directory, this means a directory whose file are not usually changing. Of course, new files may be added to the directory. An example of such an archive is a directory where you save pictures downloaded from somewhere. An archive directory will be saved incrementally while a normal directory is always completely backed up.
RAB uses a two phase backup scheme. First, the files are copied to a read/write medium which can be mounted as an usual filesystem. For example, you may use a DVD-RAM for this purpose, but things like MO drives or a partition on another hard drive are also possible. When enough data has accumulated or a checkpoint time is reached, we will write the backup to a CD. Usually, archive directories are saved incrementally, i.e. a new CD contains only new files in the directory not already on a CD. From time to time, a new complete copy is written.