FW V06.XX/HAFM SW V08.02.00 HP StorageWorks SAN High Availability Planning Guide (AA-RS2DD-TE, July 2004)

Planning Considerations for Fibre Channel Topologies
92 SAN High Availability Planning Guide
Figure 36: Cascaded fabric
One design variation is to use more than one ISL between fabric elements. This
eliminates ISLs as a single point of failure and greatly increases the fabric design
reliability.
Cascaded fabrics are well suited for applications where data access is local but not
for applications that require any-to-any connectivity. Device locality implies that
groups of servers and the storage they access are connected through the same
fabric element and that ISLs are used primarily for fabric management traffic
(Class F traffic) or low-bandwidth SAN applications. For additional information,
refer to “Device Locality” on page 102.
Ring Fabric
A ring fabric consists of a continuous string of directors or switches connected by
one or more ISLs. Each fabric element is connected to the next fabric element
(like a cascaded fabric, but with the end-point fabric elements connected).
Figure 37 illustrates a ring fabric topology.
TM
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Interswitch Link
Fabric Connection
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