From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Russ Cox" <rsc@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] [reminder] pointer to Plan 9 FAQ
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Message-Id: <20010920220326.E8D86199E8@mail.cse.psu.edu>
Date: Thu, 20 Sep 2001 18:03:21 -0400
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> ya, but 160GB disk drives can be had now. and ibm promises 400GB
> disks within a year. i'm not going to back my machine up onto
> 50 dvd-ram disks, even if they cost $0.10 each. even with an
> infiniteX dvd-ram drive, it's going to take you 1/2 an hour to
> changes the disks. ... you know, this hasn't changed much since
> the days of backing up the 11/780s at school. it took about 60
> mag tapes and 6 hrs (if you could pay full attention).

Backups are dead.  Put your data on multiple machines
and assume that not all of them will lose your data
simultaneously.

ftp://ftp.deas.harvard.edu/techreports/tr-01-01.ps.gz

The report describes a method of replica synchronization
that is straightforward but to the best of my knowledge,
hadn't been done before.  That was our excuse for building
a file system synchronization tool called tra, also described.

I keep my home directory on my standalone laptop,
my standalone desktop machine, and the Bell Labs Plan 9 file
server.  If one replica goes south, I can reinitialize
it using from another replica.  I usually sync my laptop
and the file server before I go home each night,
and I sync my laptop and my desktop probably once
a week (I'd sync those more if I were home more).
In fact, every file on my laptop and my desktop machines
(except the tra binaries) is managed by tra.  I can reformat
a disk, do a sync, and everything is back.

It's remarkably pleasant to make changes on one system
and not have to remember what they are in order to
have them propagate elsewhere.  As an on-topic example,
I don't have an internet connection in my apartment,
so I'm offline a lot.  Since my mail box is included
in the sync, though, I can read mail on my laptop at night,
delete messages, save messages into other files, and
when I sync in the morning my real mailbox at plan9.bell-labs.com
gets updated correctly despite the fact that more mail
may have arrived in the interim.  The extra processing to
make the sync program handle mail boxes is just a 750-line
file server that took about an hour to write.

</off-topic>

Russ