Specifications

Fibre Channel Over SONET (FC-SONET)
43Continuous Access and Data Replication Manager SAN Extensions Reference Guide
Dual links
A dual-link configuration is the benchmark for disaster protection, because if one
link fails, the other link will temporarily handle all data replication. A dual link
configuration that is only partially redundant is shown in Figure 10.
For enhanced fault tolerance, a customer may choose to contract with two
different providers for the two interswitch links (ISLs), including different entries
into the data center.
In the dual-link configuration, HP recommends that the maximum sustained I/O
load be limited to 40 percent of the maximum available link bandwidth. This limit
allows for instantaneous bursts of I/O activity as well as minimizing the
performance effect of a single link failure, during which the entire I/O workload is
carried by the surviving link.
Figure 10: Dual-link SONET configuration (partially redundant)
Switch W
Switch Z
Switch Y
Switch X
CXO8296A
ISL- Black
Fabric
ISL- Gray
Fabric
SONET
FC-SONET
Gateway
FC-SONET
Gateway