> > > > But what appears to be happening is that all of the data is being written > out at the end of the checkpoint. > > This happens at every checkpoint while the system is under load. > > I get the feeling that this isn't the correct behavior and i've done > something wrong. > > > It's not an actual checkpoints. It's is a fsync after checkpoint which create write spikes hurting server.
You should set sysctl vm.dirty_background_bytes and vm.dirty_bytes to reasonable low values (for 512MB raid controller with cache I would suggest to sometning like vm.dirty_background_bytes = 33554432 vm.dirty_bytes = 268435456 32MB and 256MB respectively) If youre server doesn't have raid with BBU cache - then you should tune these values to much lower values. Please read http://blog.2ndquadrant.com/tuning_linux_for_low_postgresq/ and related posts. -- Maxim Boguk Senior Postgresql DBA. http://www.postgresql-consulting.com/ Phone RU: +7 910 405 4718 Phone AU: +61 45 218 5678 Skype: maxim.boguk Jabber: maxim.bo...@gmail.com МойКруг: http://mboguk.moikrug.ru/ "People problems are solved with people. If people cannot solve the problem, try technology. People will then wish they'd listened at the first stage."
