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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.bugs.usg
Subject: Re: Some thoughts on enhancing cpio(1)
Message-ID: <6582@utzoo.UUCP>
Date: Fri, 11-Apr-86 13:43:39 EST
Article-I.D.: utzoo.6582
Posted: Fri Apr 11 13:43:39 1986
Date-Received: Fri, 11-Apr-86 13:43:39 EST
References: <150@ttrda.UUCP>
Organization: U of Toronto Zoology
Lines: 26

> ... good except for the case
> where files are moved without changing their modification time.  Then
> the files will not show up on the incremental backup but the file in the
> former directory will be removed.

As has been known at least since the V7 dump/restor system was written
(1978?), you should dump based on the most recent of the mod time and
the change time.  The change time changes when the inode changes, and
since a rename involves (temporarily) changing the link count, the change
time will reflect it.

> For a while we were losing our filesystems on a regular basis and we
> found that incremental backups are basically useless...

Actually they work fine if done right, i.e. using a proper dump/restor
system rather than cpio, and done standalone so the filesystem is not
changing underfoot.  Yes, we have lost filesystems and restored them
perfectly from full+incremental backups.

It is quite possibly true that incrementals are basically useless on a
System V using cpio for backups.
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				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry