Figure 1-1. Direct-Attached, Single-Cluster Configuration
public network
private network
storage system
EMC PowerPath Limitations in a Direct-Attached Cluster
EMC PowerPath provides failover capabilities and multiple path detection as well as dynamic load balancing between multiple ports on the same storage processor. However, direct-attached clusters supported by Dell connect to a single port on each storage processor in the storage system. Because of the single port limitation, PowerPath can provide only failover protection, not load balancing, in a direct-attached configuration.
iSCSI SAN-Attached Cluster
In an iSCSI switch-attached cluster, all of the nodes are attached to a single storage system or to multiple storage systems through redundant LANs for high-availability. iSCSI SAN-attached clusters are superior to direct-attached clusters in configuration flexibility, expandability, and performance.
Figure 1-2 shows an iSCSI SAN-attached cluster.
