They're really the same thing, but with a marketing spin on it from EMC. ESN is a combination of single sourced hardware and management software from EMC that creates a complete SAN solution from a single vendor. HDS has a similar solution with "Hitachi Freedom Data Networks" (FDN), which is more robust in my opinion. HP (which OEMs HDS arrays) and Compaq have similar solutions. HP has "Federated Data Networks" and Compaq has the "Storage Utility". We all try to make creating a SAN easy for our customers, and act as a "single throat to choke" by becoming the SAN integrator for the customer.
There are many piece parts in a SAN that need to be integrated to form a complete solution, so what better way than to have the storage vendor of your choice do it for you. Through the FCIA and SNIA, we are all working together to create the standards that need to be in place for all vendor equipment to work together and be managed from any vendor's software.
This was first published in July 2001