EMC AX150 Product Guide - Page 22

SPs. The Direct Attach example in Figure 15 on page 22 provides data access, but there is no protection in the event of a host HBA-to-SP-port failure. All access to data is lost. In the High-Availability Direct Attach illustration in Figure 15, redundancy is introduced. If this is an AX150, each host has two discrete paths to each SP and is protected in the event of an HBA, cable, SP port, or SP failure. Direct Attach High-Availability Direct Attach Figure 15. Direct-attach deployment SAN (switch) attached SANs introduce the concept of switches and fabrics. Switches expand the number of connections allowed beyond the restrictions of direct-attach configurations. With a switch, up to ten servers can connect to each SP, compared to the direct-connect limitation of two. Hosts can be configured with only one connection to the storage system. Alternately, a server may be configured for high availability, with redundant connections to the storage system. Figure 16 on page 23 illustrates eight attached servers for HA. Each server may have up to ten paths to each SP, although this configuration would limit the number of hosts that can attach to the storage system. There is a limit of ten host initiators supported per SP. Introduction to the AX150 Storage System A Detailed Review 22