Re: Configuring PostgreSQL to minimize impact of checkpoints

Quoting Rob Fielding <rob(at)dsvr(dot)net>:

> Assuming you're running with optimal schema and index design (ie you're
> not doing extra work unnecessarily), and your backend has
> better-then-default config options set-up (plenty of tips around here),
> then disk arrangement is critical to smoothing the ride.

The schema and queries are extremely simple. I've been experimenting
with config options. One possibility I'm looking into is whether
shared_buffers is too high, at 12000. We have some preliminary evidence
that setting it lower (1000) reduces the demand for IO bandwidth to
a point where the spikes become almost tolerable.

> First tip would to take your pg_xlog and put it on another disk (and
> channel).

That's on my list of things to try.

> Next if you're running a journalled fs, get that journal off
> onto another disk (and channel). Finally, get as many disks for the data
> store and spread the load across spindles.

Dumb question: how do I spread the data across spindles? Do you have
a pointer to something I could read?

Jack Orenstein

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