Backing Up Files and Filesystems
Most systems offer a variety of utilities for performing
backups, ranging from general-purpose archiving programs
cpio to programs designed for implementing
multilevel incremental backup schemes on a per-filesystem basis. When
the largest tapes held only a couple hundred megabytes, choosing the
right utility for system backups was easy.
cpio were used for small and ad hoc backups
and other data transfer needs, and the more sophisticated utilities
specifically designed for the task were used for system backups, because
their specialized abilities—the ability to span tapes and to
automatically perform incremental backups—were essential to getting the
This distinction breaks down to a great extent when a single tape can hold gigabytes of data. For example, incrementals are less important when you can fit all the important data on a system onto one or two tapes—and you have the time to do so. Large tapes also make it practical to back up a system in logically grouped chunks of files, which may be spread arbitrarily throughout the physical filesystem. A successful system backup process can be built around whatever utilities make sense for your system.
One dubious piece of advice about backups that is frequently given is that you should limit filesystem size to the maximum backup media capacity available on the system. In this view, multi-tape backup sets are simply too much trouble, and the backup process is simplified ...