Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!rutgers!att!chinet!les
From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.unix.i386
Subject: Re: 386/ix User-level Performance??
Summary: really backups
Message-ID: <9545@chinet.chi.il.us>
Date: 11 Sep 89 15:59:49 GMT
References: <472@telesoft.telesoft.com> <6750@stiatl.UUCP> <105@dumbcat.UUCP> <1144@virtech.UUCP> <14650@bfmny0.UU.NET>
Reply-To: les@chinet.chi.il.us (Leslie Mikesell)
Organization: Chinet - Public Access Unix
Lines: 35

In article <14650@bfmny0.UU.NET> tneff@bfmny0.UU.NET (Tom Neff) writes:

> 2. Having said that, anyone with a working knowledge of UNIX utilities
>can put together a useful backup proc.

Sort of... Can you separately back up the system as installed and your
own programs and modifications so that you can sanely either (a) restore
an unmodified as-purchased system or (b) add your own modifications back
after re-installing a (possibly different) system?

Does your partial backup scheme catch files that have been renamed or
moved to new locations or copied from somewhere else with the original
date intact (it won't if it is based on "find -newer" or "find -mtime").

Can you restore your partial backup on top of an earlier full backup
without running out of disk space due to the files that were deleted
between the two backups coming back to haunt you?

> 3. The advantages of cpio(1) over tar(1) go away when you have TEAM
>in the pipeline.  The tape streams and screams just fine.

They are still somewhat different, at least in the standard versions.
Tar only handles normal files and directories, while cpio knows about
special files (devices, FIFOS).  Tar always uses a 512 byte header
for every file and pads the end of each file to a 512 byte boundary.
This makes error recovery easier but the archives may be substantially
larger than cpio's.  The difference goes away if you compress the whole
thing, but that tends to make error recovery impossible.
GNUtar handles special files and has an option to store the directory
contents so that a partial restore can (optionally) delete any files
that did not exist at the time the backup was made. I'd like to
see something with this option, cpio style headers and per-file
compression like zoo.

Les Mikesell