.SAN design reference guide Vol. 1-5 785350-001

(32 to 40 ports), or a Core or Director switch (64 to 240 ports), which have higher port counts.
For a high-availability SAN, use two switches configured in a dual-fabric SAN.
Benefits
The benefits of a single-switch fabric include:
• Easy installation and configuration of servers and storage
• Maximum fabric performance because all communicating devices connect to the same switch
• Support for local, centralized, and distributed data access needs
Cascaded fabric
A cascaded fabric is a set of interconnected switches, arranged in a tree format, that have one or
more ISLs (Figure 2). You can connect one switch to one or more switches using a single ISL to
each, or connect a pair of ISLs between two switches. HP recommends that you have a minimum
of two ISL connections on each switch to provide fabric path redundancy. You should consider
using a cascaded fabric topology if you require multiple groups of devices with localized intraswitch
access.
Cascading enables you to:
• Achieve optimum I/O activity by connecting servers and storage to the same switch in the
cascaded fabric
• Easily scale the fabric over time by adding cascaded switches
Figure 2 Cascaded fabric
25090a
Cascaded fabric 25