Our bussiness do not tolerate anymore downtime (the downtime is estimate at 10 hour / year - that involves upgrade of hardware, crash of hardware), and using Slony-I 1.2.15 I have waste time to put the slave node on production. So I'm studying some replications softwares, like pgpool, pg_cluster, pg_replicator.
Pgpool has a good idea, I can connect at 2 servers or more at the same time. But I have some limitations, like Replication, Datas generated by the servers (CURRENT_DATE, CURRENT_TIME, serial, oid); so I discarded it. I tryed pg_cluster, but the documentation is very poor, and the installation was unsuccesfull.
I would like to know from you what solution you uses for avoiding downtime, so I could choose the solution that is best to my scenario and for others that is begining in Postgres and is a little lost in replication.