Re: [patch] vmfixes-2.4.0-test9-B2

From: Jamie Lokier (lk@tantalophile.demon.co.uk)
Date: Tue Sep 26 2000 - 06:23:40 EST


Peter Osterlund wrote:
> Btw, does anyone know how the seek time depends on the seek distance
> on modern disk hardware?

I know very little but I've seen it before on this list.

For larger seeks, the head is accelerated then decelerated to roughly
the right track. That time is approx. the square root of the seek
distance, which we can assume is approximately the difference in block
number on the disk.

After that, there is a settling time which is roughly constant for all
seeks, though I wouldn't be surprised to find it's a bit smaller for
really tiny seeks.

There are different rules for when there are multiple indepdendent
heads, for RAID arrays etc. (just to remind).

enjoy,
-- Jamie
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