Dell PowerVault 775N (Rackmount NAS Appliance) - Manual (Page 13)

Using EMC PowerPath in a Direct-Attach Cluster
EMC PowerPath provides failover capabilities and multiple path detection as well as dynamic load balancing between multiple
ports on the same SP. Direct-attached clusters supported by Dell connect to a single port on each SP in the storage system.
Because of the single port limitation, PowerPath can only provide failover protection in a direct-attached configuration.
SAN-Attached Cluster
In a SAN-attached cluster configuration, all of the cluster nodes are attached to a single storage system or to multiple
storage systems through a SAN using a redundant switch fabric. SAN-attached cluster configurations are superior to direct-
attached cluster configurations in configuration flexibility, expandability, and performance.
See " Fibre Channel Switch Fabric " for more information on Fibre Channel switch fabrics.
Figure 1-2 shows a SAN-attached cluster configuration.
Figure 1-2. SAN-Attached Cluster Configuration
Configuring Active and Passive Cluster Nodes