> SHORT ANSWER: Segregating partitions reduces seek time. Period.
>
> LONG ANSWER: Reads and writes tend to be grouped within a partition.
> For
> example, if you're starting a program, you're going to be doing a lot
> of
> reads somewhere in the /usr partition. If the program uses temporary
> files,
> you're going to do a lot of reads & writes in the /tmp partition. If
> you're
> saving a file, you're going to be doing lots of writes to the /home
> partition. Hence, since most disk accesses occur in groups within a
> partition, preference should be giving to reducing seek time WITHIN a
> partition, rather than reducing seek time BETWEEN partitions.
keep in mind that only around half of the seek time is because of the
partition! Taking an IBM 120GXP as an example:
Average seek: 8.5ms
Full stroke seek: 15.0ms
Time to rotate disk one round: 1/(7200/60)*1000 = 8.3ms
Then, the sector you're looking for, will, by average, be half a round
away from where you are, and thus, giving the minimum average seek time
8.3/2 = 4.15ms or something like half the seek time. Concidering this,
you may gain a maximum <= 50% gain in using smaller partitions.
btw. anyone that knows the zone layout on IBM drives?
roy
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This archive was generated by hypermail 2b29 : Tue Dec 31 2002 - 22:00:07 EST