Information Storage and Management: Storing, Managing, and Protecting Digital Information in Classic, Virtualized, and Cloud Environments, Second Edition

Appendix C

SAN Design Exercises

Exercise 1

An organization wants to implement a full mesh FC SAN. Following is the specification of servers, storage systems, and switches involved in the design:

• Number of hosts = 30. Each host has two single-port HBAs.
• Number of storage arrays = 4. Each array has eight front-end ports.
• Available switching elements:
  • Modular FC switches with minimum 16 ports. The number of ports in a switch can be increased up to 32 ports by adding additional port cards. Each port card includes 8 ports.
  • At least two interswitch links (ISLs) must exist between any two switches to ensure high availability.

At a minimum, how many switches are required to meet the given requirements? Justify the number of ports in each FC switch considering cost optimization.

Solution

Each FC switch can provide a maximum of 32 ports. Considering 32 ports per switch, four switches provide a total of 128 ports. In four 32-port switch full mesh topology, 24 switch ports are used for ISLs, and the remaining 104 ports can be used for node connectivity. However, the fabric requires 92 ports for node connectivity. Therefore, to optimize the cost, the organization should deploy three 32-port switches and one 24-port switch. In this implementation, the number of switch ports available for node connectivity is 96, of which 92 ports can be used to connect nodes and the remaining 4 ports are ...