Re: Need to tune for Heavy Write

On Thu, Aug 4, 2011 at 2:34 AM, Willy-Bas Loos <willybas(at)gmail(dot)com> wrote:
> On Thu, Aug 4, 2011 at 6:56 AM, Adarsh Sharma <adarsh(dot)sharma(at)orkash(dot)com> wrote:
>> After this I change my pg_xlog directory to a separate directory other than
>> data directory by symlinking.
>>(...)
>> Please let me know if I missing any other important configuration.
>
> Moving the pg_xlog to a different directory only helps when that
> directory is on a different harddisk (or whatever I/O device).

Not entirely true. By simply being on a different mounted file
system this moves the fsync calls on the pg_xlog directories off of
the same file system as the main data store. Previous testing has
shown improvements in performance from just using a different file
system.

That said, the only real solution to a heavy write load is a heavy
duty IO subsystem, with lots of drives and battery backed cache.