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Switched Fabric Connection in Dual Controller
In this type of connection, the channel link bypass is provided by external FC switches. Each
application server shown in the illustration below is equipped with two HBAs with FC links,
connecting via two FC switches to the SFP ports on individual controllers.
Channels
Controller A
Controller B
Host
CH0, CH1, CH2, CH3
CH0, CH1, CH2, CH3
Configuration information
Number of controllers
2
Host servers
4 (or more via FC switches)
FC switches
2 (or 1 into 2 zones
Data path connection
Fault-tolerant data paths
Each logical partition is redundantly mapped to multiple host channel IDs in an AAPP (Active-
Passive- Passive-Passive) configuration. Logical volumes are managed by either controller A or
controller B. The passive IDs will only become functional when a single controller fails in the
system.
The MPIO driver is needed on the application servers. This driver communicates with the
system firmware and performs load balance and automated distribution of I/Os across the
preferred paths (active IDs on data paths). TPGS (Target Port Group Service) is supported so
that the I/Os are routed to the preferred paths.
You can refer to the ID tags on the host links to see the related logical volume mapping and
cable links routing paths. The connection above can withstand failure of a single component
such as controller, HBA card, cable, or FC switch.
