[ale] On swap space (was Re: who is eating my drive)

Pat Regan thehead at patshead.com
Tue May 31 19:07:16 EDT 2011


On Tue, 31 May 2011 18:24:09 -0400
Jim Kinney <jim.kinney at gmail.com> wrote:

> My (30 seconds of) digging shows that drive rotation speeds vary to
> keep the data rate passing under the head nearly constant thus making
> the data rate out of the drive nearly constant for reads larger than
> the cache. seek time is related to disk diameter and how fast the
> head arm and swing.

That should only be true of old cdrom drives.

Hard drive platters have way too much momentum at 7200 RPM (or 15k!) to
adjust speed between reads/writes.  Hard drives have a varying number
of sectors per rotation.  More data passes under the head on the outer
tracks.

I'm being told I have to leave the house now, so I can't keep jibber
jabbering about this :)

Pat


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