> >
> > The bottom line: Read performance for a RAID-1 device is better than a
> > single (JBOD) device. The bigger the n in n-way mirroring gives better
> > read performance, but slightly worse write performance.
> >
> But using n-way mirrors will also increase cpu utilization during reads
> -
> or am I wrong? - because of the cycling process.
CPU utilization is not increased for reading by higher n's in n-way
mirroring. Only one device is asked for the data. The overhead for the
balancing is small. If cpu utilization goes up while reading, it is
because your throughput is higher :-)
Memory bus utilization is increased (thus increase in CPU utilization)
for writing more n's in n-way mirroring. This is because the data is
duplicated across the memory bus n times. This is true with IDE and
SCSI.
<>< Lance.
