Fabric Scalability; Redundant Fabrics - HP 316095-B21 - StorageWorks Edge Switch 2/24 Planning Manual

Figure 45: Redundant fabrics
Some dual-attached devices support active-active paths, while others support only
active-passive paths. Active-active devices use either output path equally, and
thus use both fabrics and double the device bandwidth. Active-passive devices use
the passive path only when the active path fails.
When deploying redundant fabrics, it is not required that the fabrics be
symmetrical. As an example, single-attached devices, such as tape drives and
noncritical servers and storage, can be logically grouped and attached to one of
the fabrics.

Fabric Scalability

A scalable fabric allows for nondisruptive addition of fabric elements (directors
and switches) or ISLs to increase the size or performance of the fabric. Scalability
also relates to investment protection. If a core edge switch is replaced with a
newer or higher port count switch, it is often valuable to use the existing switch
elsewhere in the fabric (at the edge).
SAN High Availability Planning Guide
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Planning Considerations for Fibre Channel Topologies
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