On Jul 9, 2012, at 10:51 PM, Maxim Boguk wrote: > > > 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
So use bla_bytes instead of bla_ratio? > (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) I'll take a look. > > 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. yeah, I saw that I guess I didn't put 2+2 together. thanks.
