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From: ggs@ulysses.homer.nj.att.com (Griff Smith)
Newsgroups: comp.unix.questions,comp.unix.microport
Subject: Re: dump/restore
Message-ID: <10782@ulysses.homer.nj.att.com>
Date: 30 Oct 88 23:41:25 GMT
References: <178@celerity.UUCP> <12433@steinmetz.ge.com> <326@auspex.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 46

In article <326@auspex.UUCP>, guy@auspex.UUCP (Guy Harris) writes:
> ... Probably, if you want "dump" for the System V file system, you should
> start with the 4.1BSD version, and whack it as necessary to support file
> systems with a block size other than 1K (and maybe throw in goodies from
> the 4.2BSD and 4.3BSD ones as well, such as "remote magtape" support and
> the multiple buffering stuff).

I (and others, I suspect) have done part of this.  I started with the
4.1dump that comes with 4.[23]BSD and then made it work with System
Vr3.  An associate added network support to my stuff.  Performance is
unimpressive; similar to tar and cpio.  The 1k blocks really slow it
down.  I haven't had the courage (or time) to do all the things
required to deal with other block sizes.

> "restor(e)" is a different question.  You should definitely start with
> the 4.1BSD one (since, as I remember, it understands the "s_tfree" and
> "s_tinode" fields, while the V7 one and even the S3 one didn't).

If you are starting with 4.3BSD source, the 4.3BSD restore is a good
starting point.  The `4.2BSD compatibility mode' works just fine.
4.3 restore was an easier port than 4.1 dump.

> I suspect that, if S5R4 doesn't have "dump" or "restor(e)" for the S5
> file system, it's only because they don't like it and think
> "volcopy"/"finc"/"frec"/"frick"/"frack"/... are better, or because they
> don't have the effort to invest in bringing it back.

My guess is that most of us don't know much about it any more.  Tribal
memory is short.  Many of the old guard who knew about dump/restor have
`died'.  Some others have heard legends of a place where backups are
fast and convenient, but they are usually dismissed as the ravings of
the old generation.

Another point: backup devices on the 3B2 processors I have used have
been incredibly slow, which lowers the advantage of fast dump
programs.  Few of our System V users realize how fast backup can be
when you use the 4.3BSD dump with a 125 ips tape drive and a fast file
system.  I'll take part of that back.  Volcopy onto a 200 ips tape
drive on the IBM mainframe at the Comp Center goes like a bat out of
hell, but you don't maintain the speed when you do incrementals with
cpio.
-- 
Griff Smith	AT&T (Bell Laboratories), Murray Hill
Phone:		1-201-582-7736
UUCP:		{most AT&T sites}!ulysses!ggs
Internet:	ggs@ulysses.att.com