On Thu, 2007-03-29 at 15:13, Dmitry Koterov wrote:
> No, but disks are about 120 MB/s speed, peak writes during CHECKPOINT
> are only 20-30 MB/s, and there is no disk read activity at all, so -
> no matter where the xlog resides.
>
> But now seems bgwriter tuning gets some effect, CHECKPOINT is running
> faster (about 2-3 seconds instead of 10-15). It is still beats the
> performance, but less.
Well, I assume bgwriter isn't the only thing writing to those disks.
Which would mean that your bgwriter output is random access not
sequential. Which would mean putting pg_xlog on another set of drives
where it wasn't competing with other postgresql (and system) processes
for drive access would speed things up.
Or getting a good battery backed RAID controller. That's the first step
to building a fast db server if you're using built in storage.
but I could be wrong or have misunderheard what you were saying.
