SECURING FIBRE CHANNEL FABRICS - Brocade

FC Fabric Features and ServicesAnd although you can architect a SAN for two or three of these factorsat the same time, it will usually be at the expense of the other factors.For example, you can have a highly redundant, high-performance fabricbut it will most likely not be very scalable. Finding the right balanceamong these factors is more an art than a science.Table 5 shows how these four design factors are interrelated for thedifferent topologies described in this section.Table 5. Fabric topology design factorsTopology Performance Scalability Redundancy CostCascade Poor Poor Poor $Ring Good Poor Good $Full mesh Excellent Poor Excellent $$Partial mesh Good Good Good $$Core-edge Excellent Excellent Good $$$Resilient-core-edge Excellent Excellent Excellent $$$$For further information on this topic, Principles of SAN Design, SecondEdition, by Josh Judd, is highly recommended.Dual FabricsAs with any network, FC fabrics should be designed without any singlepoints of failure. From an architectural and design point of view, thisredundancy is accomplished by using a dual-fabric architecture, asshown in Figure 15. Servers must also have multipathing input/output(MPIO) software running to load balance the traffic between the twopaths and to fail over to one path in the event of a path failure. If anyhardware component failure occurs in a fabric, starting from the hostHBA through to the disk controller, no production downtime will beincurred since there is an alternate path for the traffic.Securing Fibre Channel Fabrics 35