Managing Multi-File System Backup Using dump/restore

Yufan Hu

As UNIX system administrators, many of us are still using our good old friends, dump and restore, to do backups and restores for our UNIX file systems. dump and restore are some of the oldest and most popular backup tools used on many UNIX systems, especially those derived from BSD.

Over the years, the combination of dump and restore has proven its reliability and simplicity. Small is beautiful has been the philosophy of programming since the very beginning of the UNIX system. dump and restore are small, reliable, and flexible. They are not only able to do backup jobs independently, but are also able to be integrated with other programs to complete more sophisticated jobs.

Root is Relative

On UNIX, the file system refers to the entire directory tree starting from the root, /. From a user's point of view, there is no concept of a partition or a disk. Everything is located within this giant directory.

For administrators, the view is a bit different. We still have the concept of disk and disk partitions. We put a disk or a partition into the overall file system by mounting the disk or partition onto a directory. After mounting, the contents of the root directory of the disk become the contents of the mounting directory. The overall file system is thus expanded without the users noticing the difference, except for the added directory tree branch. From the administrator's view, we call the directory tree in a single disk or disk partition a file system. We call the directory on which we mount the file system the mounting point of that file system.<>