Various rules and limits exist on how storage hardware can be attached together. The limits may be determined by hardware design, architecture restrictions, performance considerations, or support concerns. Your IBM® marketing representative can explain these configuration limits and help you use them in your planning.
For each disk unit type, first plan for the I/O adapter that are needed and then for the I/O processors that are needed. After planning the number of I/O processors that are needed for all disk unit types, use the total number of I/O processors to plan for the number of buses that are needed.