This is one of the important parts because we are going to define some levels about our service that are provided to customers such as Gold, Silver, Bronze.
Before going further, you must define what kind of service you will provide. I will try to explain little bit.
Gold for me means, best CPU, best memory and FC SAN storage
Silver can be mixed storage tier.
Bronze should be lowest CPU and memory and SATA disks. All you have to do is to define what service you have.