suggestions for optimal filesystem-layout over multiple harddrives?

[Geert Hendrickx]

Hi, 

using multiple harddisks can increase performance, since I/O can be done
in parallel.  But what would be an optimal filesystem-layout on, say,
two disks of equal size?  Swap should evidently be spread equally over
the different drives.  As for the filesystems, say I'd have a large /usr
and /home, each on one harddrive, and smaller /, /var and /tmp which
could reside on either disk.  / and /usr would be mostly read-only.  

Any suggestions?  

GH