Processor idle time with too few disks

[Pritch5000]

Does anyone know info about the optimum ratio for the number of processors vs hard disks to ensure minimum processor idle time waiting for I/O requests.

thanks

 

[comtec17]

Hard drives do not drive processor utilization, it is the I/O on those disks that do.

 

[Pritch5000]

Thaks for the reply.
But I'm not sure I understand your reply...

The more hard disks you have the father I/O requests will be, this is because you increase the number of heads on the disks and thereby increase the access times to your data.

Processors work so quickly that they can have idle time waiting for I/O requests to complete.

To counter this we can increase disk speeds and use better RAID controllers with battery backed cache for wirte-back and faster thruputs.

Then we come to increasing the number of disks and RAID controllers.

Why question is: Is this right? and what is the optimum ratio of disks and processors.

I ask this because we are about to do some testing on an 8-way box but will only be able to use 8x 36K disks, across two RAID controllers.

Any further comments greatly appreciated.
pritch.