From: | johnnnnnn <john(at)phaedrusdeinus(dot)org> |
---|---|
To: | "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Scaling further up |
Date: | 2004-03-02 23:25:41 |
Message-ID: | 20040302232540.GA4102@performics.com |
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Lists: | pgsql-performance |
On Tue, Mar 02, 2004 at 02:16:24PM -0700, scott.marlowe wrote:
> It's a common misconception that faster RPM drives are a lot faster,
> when, in fact, their only speed advantage is slight faster seeks.
> The areal density of faster spinning hard drives tends to be
> somewhat less than the slower spinning drives, since the maximum
> frequency the heads can work in on both drives, assuming the same
> technology, is the same. I.e. the speed at which you can read data
> off of the platter doesn't usually go up with a higher RPM drive,
> only the speed with which you can get to the first sector.
This would imply that an upgrade in drive RPM should be accompanied by
a decrease in random_page_cost, correct?
random_page_cost should be set with the following things taken into
account:
- seek speed
- likelihood of page to be cached in memory by the kernel
- anything else?
Sorry, i realize this pulls the thread a bit off-topic, but i've heard
that about RPM speeds before, and i just want some confirmation that
my deductions are reasonable.
-johnnnnnnnnnnn
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