Re: [9fans] Fossil+Venti on Linux

[a@9srv.net]

I'm not running Linux, but I've run venti+fossil on Mac OS X for testing. I
intend to use venti there regularly once I figure out how to get OS X to let
me get at a raw partition that isn't mounted (anyone?).

I don't think venti+fossil will do what you're looking for, however, at least
not without some additional machinery. Fossil doesn't do any replication or
fail-over: it must talk to zero or one ventis. Venti doesn't automatically
replicate anything, either, although that's pretty easy to script if you're
willing to accept the exposure of a cron job. It's true you could run multiple
fossils off one venti, but they'll be logically distinct (just getting the block
aggregation benifits of sharing a venti backing store).

I believe the Plan B folks did some work with fail-over (amongst other
things) that might be applicable. Beyond that, if you want to get what you
want from venti+fossil, you'll need to inject a filter in front of one of those
two to do the fail-over (and handle all the fun of tracking writes and
propagating them when the server comes back, and so on).

If you're looking to back up *existing* Linux boxes, then fossil might not
be what you want anyway. Take a look at vbackup(8) and friends (I'm
trying to convince it I'm on an HFS+ partition). You'll have to figure out
the correct procedures for your site, but the examples are pretty useful.
Still no automatic fail-over, but a cron job could probably get you
replication.
Anthony