Dell EMC Metro node 7.1 Product Guide

Directors

A metro node director is the component that process the I/O requests from the hosts in a metro node environment. It interacts with the backend storage arrays for servicing the I/Os.

A director has two I/O modules for servicing I/Os from the arrays; one for the connectivity with the storage arrays on the back end, and another for connecting to the hosts on the front end. The management module in the director is used for management connectivity to the directors and for intra-cluster communication. The local communication module is completely dedicated to intra-cluster communication.

The front-end ports on all directors can provide access to any virtual volume in the cluster. Include multiple front-end ports in each storage view to protect against port failures. When a director port fails, the host multi-pathing software seamlessly fails over to another path through a different port, as shown in the following figure:

Combine multi-pathing software plus redundant volume presentation for continuous data availability in the presence of port failures.

Back-end ports, local COM ports, and WAN COM ports provide similar redundancy for additional resilience.

Each director can service I/O for any other director in the cluster due to the redundant nature of the global directory and cache coherency.

If one director in the engine fails, another director continues to service I/O from the host.

In the following figure, Director 1-1-A has failed, but Director 1-1-B services the host I/O that was previously being serviced by Director 1-1-A.