Thank you for your answer.
Planning to use hardware raid (3ware) as the rebuild is easier/faster.
I should have stated that I know nothing about SAS.
I deduct from your answer that a SAS of 16 drives, for example, can be considered as a single drive or volume and partitioned accordingly (ignoring allowance for hot swap etc) and that this partitioning can be performed as well as making the SAS a raid 5 or 6. Is that correct?
Can anyone suggest a tutorial or similar material on SAS? I need to learn things like how it interfaces to a motherboard, setting up etc.
I've read somewhere a suggestion that even a SCSI SAS system plugs straight into a sata connector on the motherboard but I doubt that it is that simple.