Xref: utzoo comp.unix.questions:10000 comp.unix.microport:1902
Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.unix.questions,comp.unix.microport
Subject: Re: dump/restore
Keywords: cpio is not a real backup program
Message-ID: <366@auspex.UUCP>
Date: 31 Oct 88 20:20:25 GMT
Article-I.D.: auspex.366
References: <178@celerity.UUCP> <12433@steinmetz.ge.com> <77@usl-pc.usl.edu> <44433@beno.seismo.CSS.GOV>
Reply-To: guy@auspex.UUCP (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 14

>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....