Strategies for Data Protection - Brocade

Storage-Centric vs. Network-Centric SAN ArchitecturesWhich solution is better depends on the projected growth in both storagecapacity and server attachment, as well as availability needs.Unfortunately, some customers have inherited complex meshed SANtopologies due to the spontaneous acquisition of switches to satisfygrowing port requirements. At some point, fabric consolidation may berequired to simplify cabling and management and to provide stabilityfor storage operations. Without a solid foundation of a well-designedmanaged unit of SAN, higher-level data protection solutions are alwaysat risk.A managed unit of SAN can also be characterized by its intended functionality;and functionality, in turn, can drive a specific SAN topology. Ahigh-availability SAN, for example, requires redundancy in switch elementsand pathing, as well as management tools to monitor andenforce continuous operation. However, a SAN designed for secondtierapplications may not justify full redundancy and be adequatelysupported on a more streamlined topology. In addition, a SANdesigned specifically for tape backup has very different requirementscompared to a production SAN. Tape is characterized by large block,bandwidth-intensive transactions, while production disk access is typicallydistinguished by small block and I/O-intensive transactions.Because tape operations consume bandwidth for extended periods oftime and are sensitive to fabric events, customers can implement twoseparate SANs or leverage Virtual Fabrics to isolate production diskaccess from backup operations. As a separate tape SAN, a flat SANtopology that avoids potential ISL oversubscription is recommended.An optimized SAN topology can also be affected by the server technologyused to host applications. Blade servers and blade SAN switches,in particular, can adversely impact the consumption of switchaddresses, or Domain IDs, and limit the total number of switchesallowable in a SAN unit. A new standard for N_Port ID Virtualization(NPIV) has been created to address this problem. An NPIV-enabledgateway presents logical hosts to the SAN and thus eliminates theaddition of another switch element, Domain ID assignment, andinteroperability or switch management issue. Brocade Access Gateway,for example, leverages NPIV to bring blade servers into the SANwithout requiring administrative overhead to monitor Domain ID usageand potential interoperability conflicts. As long as the edge SANswitches are NPIV aware, larger populations of blade servers can beaccommodated without limiting the scalability of the SAN topology.Strategies for Data Protection 15