Open Source for mission-critical systems (slightly OT)

[Lennart Sorensen]

On Thu, Jun 02, 2005 at 11:55:31AM -0400, Andrew Hammond wrote:
> Slony1 provides async replication for postgres. Prior to slony, there
> was ER-Server. There's also Mammoth Replicator which has been around for
> quite a while but is commercial software.
> 
> If you want multi-master then you're right, there's nothing (yet) for
> postgres.

At the time we did a running log of transactions at the application
level, which could then be run against a backup server at regular
intervals.

ERserver and slony just weren't what we were looking for.  Besides
having the ability to query from multiple servers would have been great
too, given we ended up running on a quad xeon HT (around 1.6ghz I think)
to have fast enough response at busy times.  The web servers and image
processing was easy to distribute on multiple machines of course.

Unfortunately I am quite aware how hard doing live syncrhonization of
databases is, and I wouldn't want to try and implement it.  Staying in
sync is no big deal, but getting back in sync after downtime of one
server is a nightmare when the system is in use.  If you could pause it,
stop the active one, copy it, then start them in sync it would be
reasonably easy.  That generally isn't what people want though.

Lennart Sorensen
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