dump/restore

[Guy Harris]

>This is real important as anyone who has tried to restore a corrupted
>disk from a cpio "backup" and has found that the "backup" is too big to
>fit on the disk it came from can tell you.

Furthermore (although this isn't as likely to be a problem), neither
"cpio" nor "tar" know about files with "holes" - they just read the file
and, if they hit a hole, the file system code dutifully gives them a
block full of zeroes, which as far as they're concerned is a disk block
full of zeroes.

This means that if you use "cpio" or "tar" to dump and restore a file
system containing files with holes, you may again fild that the backup
won't fit, because those holes will get assigned blocks when you restore
the dump....