Re: Scaling further up

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