On Sun, Feb 27, 2011 at 12:10:36PM -0800, John R Pierce wrote: > are made to the master server, but reads are done to either. note you > do NOT want to use block level replication like drbd for this as the > drbd slave can not be actively mounted, nor could the slave instance of > postgres be aware of changes to the underlying storage, rather you would > use the streaming replication built into postgresql 9.0. Note that with drbd, you can have a piece of hot standby hardware sitting there to take over the filesystem in real time, in the event the original master blows up or something. My experience with systems designed like this is that they are a foot-bazooka: the only real utility I ever saw in them was to increase on-call hours for sysadmins after they blew off their own foot (and too often, my database) doing something tricky with the standby server. If it were me setting it up, I'd think the streaming replication approach a better bet. Not that anything will save you when someone else has root and decides to play with a production server. I believe that Greenplum sells a system based on Postgres that is supposed to do some kind of distributed cluster thing. I don't understand the details and it's been a long time since I had any look at it. I think it's intended to compete in the scalability rather than the availability market. Maybe someone around here knows more. The only people I'm aware of who really do this sort of thing for availability are Oracle with RAC, and Oracle with some mostly-works clustering stuff in MySQL. I have never met a happy customer of the former, but I've heard some people tell me it's real impressive technology when it's working. (The unhappy people seemed mostly unhappy because, for that kind of coin, they would like it to work most of the time. I know at least one metronet deployment that didn't work even once for two years.) In the case of the MySQL stuff, there are some trade-offs in the design that make my heart sink. But maybe for the OP's application it will work. A -- Andrew Sullivan ajs@xxxxxxxxxxxxxxx -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
