On Wed, Feb 6, 2013 at 7:49 AM, Kevin Grittner <kgri...@ymail.com> wrote:
> "a...@hsk.hk" <a...@hsk.hk> wrote: > > Johnny Tan <johnnyd...@gmail.com> wrote: > > >>shared_buffers = 48GB# min 128kB > > > From the postgresql.conf, I can see that the shared_buffers is > > set to 48GB which is not small, it would be possible that the > > large buffer cache could be "dirty", when a checkpoint starts, it > > would cause a checkpoint I/O spike. > > > > > > I would like to suggest you about using pgtune to get recommended > > conf for postgresql. > > I have seen symptoms like those described which were the result of > too many dirty pages accumulating inside PostgreSQL shared_buffers. > It might be something else entirely in this case, but it would at > least be worth trying a reduced shared_buffers setting combined > with more aggressive bgwriter settings. I might try something like > the following changes, as an experiment: > > shared_buffers = 8GB > bgwriter_lru_maxpages = 1000 > bgwriter_lru_multiplier = 4 > Thanks Kevin. Wouldn't this be controlled by our checkpoint settings, though?
