GNU-tar vs dump(1)

[Rudy.Nedved at rudy.fac.cs.cmu.edu]

The goal of dump is to restore the system to the state of the dump. The
goal of tar is to archive information for later retrieval. In general,
these goals overlap.

Problem 1: tar does not deal with empty data blocks in a file. It asks
the system for the block and the system gives it a block of zeroes. When
you restore a disk that was very full from backup...you will end up
using more disk space then was actually there since the null blocks will
be written out. This can be partially solved by having tar read the
blocked or raw disk device file but that means it must be system dependent.

Problem 2: I don't know about gnu-tar but standard tar has limits on
filenames....If you have long file names in your system, you may lose
that file on restore or at least have the file name truncated.

Problem 3: In general, tar is system independent for good reasons so it
is possible you may lose information critical to the complete restore of
your disks...Maybe they don't have this problem with gnu tar.

I am curious.

-Rudy