At first glance, it might seem that the number of ports is a relatively insignificant factor when choosing a storage array, switch or host bus adapter (HBA). Application requirements, operating system support, device features, performance and scalability are all factors to consider--the number of ports is almost an afterthought. But the number of ports plays an increasingly important role in the application's availability and performance, as well as the cost of the storage device and how complex it is to manage.

Think of ports as gates into arrays and switches; if these gates are congested, the fastest arrays and switches won't be able to live up to their potential. Therefore, the number of required ports into a storage system is determined by how much traffic the storage system must handle.