filesystem performance

[Mark Wong]

On Wed, May 6, 2009 at 2:25 AM, Anthony Pankov <ap00 at mail.ru> wrote:
> Hello Mark,
>
> May i ask a question while more expierenced people is waking up?
>
> I don't fully understand the target. For what filesystem should be
> optimized?
>
> I expect a patterns of recorded IO calls when pgsql perform typical
> operations with statistics and in-depth analysis.

The angle we're trying to look at is from a sizing perspective.  In
order words we want to have an idea of what to expect before we do it.
 For example, if I have 10 drives, what can I expect if I configure
them in a RAID 10 configuration?

> Are you sure there is ą strong relation between fio benchmark result and
> PostgreSQL performance?

Sorry, this was something I was trying to make clearer originally.
No, I don't think there is a strong relationship between fio and
PostgreSQL, but these i/o patterns we are simulating do give us a
rough estimate of we can expect.  For example, in workloads with lots
of update and inserts into a database will generate a lot of
sequential writes to the database logs, which we can physically
isolate onto it's own lun.  Similarly, in some warehousing
applications there may be a table that is always scanned and read
sequential, which also can be on its own physical lun.

Regards,
Mark