why separate filesystems?

[P.Garbha]

In article <1053 at p4tustin.UUCP> carl at p4tustin.UUCP (Carl W. Bergerson) writes:
>Performance:
>
>	"Smaller filesystems are faster" - Xenix Installation Guide
>
>	This is generally true for all versions of *ix.

Can you explain why? Becuase I cannot see why it should be like that.
The only reason I can think of is reduced head-movement, but if you
divide one disk into to parts, that effectively defeats that, by
having to move the head back and forth between the parts.

I tend to believe that dividing a file system makes it slower, because
you get less free space on each part, and UNIX file-system with little
free space is slower. You also get greater chance that one partition
will run out of space, or i-nodes. You will also use up more
disk-space, by having to duplicate files on the filesystems -- unless
you have soft-links.