David Brownlee writes:
> 	Would there be any sense in creating two RAID1 partitions across
> 	a pair of disks - one for the system partions and swap and one
> 	for the data?

Sure..  

> 	The thought is to give two I/O queues, plus the ability to
> 	repartion the data side without touching the system.

Plus if there is a serious error on one partition (e.g. you end up with a real 
physical read error) only that one partition will be in degraded mode, and 
you'll still benefit from having RAID on the other (non-failed) parts of the 
disk.
 
> 	Would there be any chance it could degrade the performance of
> 	the system?

I've not done any real benchmarking on exactly that, but it shouldn't be
any worse than partitioning a disk without the RAID. 

FWIW, I usually setup a pair of partitions to be used (non-RAIDed) for 
bootblocks+kernels, a pair in a RAID set for /, a pair in a RAID set for 
swap, and a pair in a RAID set for '/u1' (or whatever).

Later...

Greg Oster