Sunday June 06, 2004 abcd - automatic backup copy daemon - faking NFS.
Recently at work, I started doing backups by simply using a spare disk (because they are so cheap nowadays) rather than use some kind of removable media. This reminded me of something I did a long time ago.
Back in 1985, when I worked for the Sun distributor in Australia, we were trying to sell Suns to a company in Adelaide. This company wanted to see the brand spanking new NFS that Sun Microsystems Inc. in the US had just invented but hadn't released. We (only being a Sun distributor) couldn't get hold of it, but we still wanted to give the potential customer a feel for what it would be like.
So I wrote a small program called abcd (automatic backup copy daemon).
It continually monitors and copies files from one filesystem to another using either cp or rcp if the files have changed. Note the nowadays, the second filesystem could be on another machine if the file system is NFS mounted.
This means that the backup disk or machine should have an identical copy of the filestore being monitored, give or take a little bit. Not exactly NFS as it's a one way thing, but good enough to demo.
After writing it, it was obvious that this was a great way of keeping two disks in sync, and therefore had the potential to be a means of backing up your work.
I released this to one of the USENET newsgroups in 1988 and it got quite popular for a while. I took out the bits and polished them off a year or so ago. It still works fine.
Note that there are lots of similar programs (like rsync) that can do this nowadays and are being actively maintained.
November 1985 (when this all originally took place) was the time of the first Australian Formula 1 Grand Prix (through the streets no less). I was staying in one of the hotels in the middle of the town, and could see (and HEAR) the race from my bedroom balcony. One of the race teams were staying at the hotel too, so it was quite an amazing time.
( Jun 06 2004, 12:16:31 PM PDT ) [Listen] Permalink
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