Spectra TFinity User Manual page 78

Chapter 2 — Architecture Overview
Controller Failover
The BlueScale Controller Failover feature uses two RIMs or two RIM2s that
are configured as a failover pair. One RIM in the pair is the primary
controller and the other is the secondary controller. From the host
perspective, the primary controller is the only controller present. The
secondary controller is not visible to the host.
Figure 34 shows a simplified view of how the failover pair operates. Port A
on each controller in the pair is connected to the same Fibre Channel
switch. Both ports have the same configuration, except that the primary
operates in target mode and the secondary is not active.
During normal operation, the active Fibre Channel port (port A) on the
primary controller receives and processes the media changer commands
sent from the host. The active port on the secondary controller does not
receive or process the media changer commands from the hosts.
The two controllers use the library's internal communication bus to
monitor each other and to maintain a cache of the library's inventory
database.
November 2020
Note: You cannot mix a RIM and a RIM2 in failover pair.
SAN
SAN
Robotic control path (target port)
Internal communication bus (mirror inventory & partner monitor)
Figure 34 Paired RIMs configured to provide failover redundancy.
Note: The paired ports on each controller can be connected to separate
SANs and used simultaneously. A failure of the primary
controller causes both connections to failover to the secondary
controller.
A
Primary Controller
B
A
Secondary Controller
B
Before failover
A
Primary Controller
B
A
Secondary Controller
B
After failover
User Guide—Spectra TFinity Library
Redundant Connectivity
78