Hi there, I am currently looking into replicated two-node master/slave PostgreSQL environments. Lately I've heard more and more people recommend replicating data from the master to the slave at the disk device level as opposed to the DBMS level (Slony-I). On Linux, usually DRBD is recommended for this, which is basically RAID-1 via a network connection, i.e. DRBD copies everything that the master writes to its disk to the slave.
What I keep wondering: Isn't there substantial risk involved? I mean, suppose the master fails in the middle of a write. Isn't there the possibility that this corrupts the database? How robust is PostgreSQL's on-disk file format and write caching strategy against failures like this? With something like Slony-I some data may not be fully copied to the slave when the master crashes. So there may be data loss. But there isn't the risk of database corruption. Or am I missing something here? Thanks, -Thomas ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
