To support the the number of I/O operations we generated we required large amount of I/O bandwidth which meant multiple I/O paths. Since we didn't have FC switches available at our disposal, we had to use direct links. We kept on adding I/O paths until we hit 350,000 number. At this stage we had twelve 4Gbps FC links and for that we needed 3 arrays with 4 FC ports each. Hence 3 arrays.

I am sure EMC has sizing guidelines for designing a storage infrastructure based on I/O requirements. You can check EMC website or talk to a local EMC rep.

Chethan