Am 19.08.2015 um 10:24 schrieb John Hodrien <J.H.Hodrien at leeds.ac.uk>: > On Wed, 19 Aug 2015, Jatin Davey wrote: > >> Hi All >> >> We use CentOS 6.6 for our application. I have profiled the application and find that we have a heavy requirement in terms of Disk writes. On an average when our application operates at a certain load i can observe that the disk writes / second is around 2 Mbps (Average). > > Initial thought is, do you really care? 2Mbps is peanuts, so personally I'd > leave everything at the defaults. There's really no need to optimise > everything. > > Obviously the exact type of writes is important (lots of small writes written > and flushed vs fewer big unsynced writes), so you'd want to poke it with > iostat to see what kind of writes you're talking about. to address this we use (sysctl) vm.dirty_expire_centisecs vm.dirty_writeback_centisecs furthermore check the fs alignment with the underlying disk ... -- LF