Spectra Logic Spectra T950V User Manual page 69

Chapter 2 — Architecture Overview
After you resolve the problem, the controller that originally caused the
failover becomes the secondary controller in the failover pair. The failover
pair reverts to the original primary/secondary relationship the next time
the LCM is restarted.
The BlueScale Controller Failover feature only affects the operation of the
library's controllers. Controller Failover does not detect if the controller is
accessible by the host. To take advantage of the feature, the host must be
configured to retry failed commands. This ensures that commands that fail
when the library connection to the primary controller is disrupted get re‐
issued after the connection to the secondary controller is established. The
retry timing must be configured to allow for the time lag inherent in the
process of disabling the host's connection to the primary controller and
enabling the connection to the secondary controller.
Exporting Drive Redundancy
As an alternative to controller failover or for drives, which cannot be
configured with controller failover, you can select multiple drives or RIM2s
as controllers for a single partition, and export the same changer interface
over them to provide redundancy, as long as your data storage software
can support this.
Drive Connectivity Failover
The full‐height Fibre Channel drives used with the library are equipped
with two Fibre Channel ports. The two Fibre Channel ports cannot be used
simultaneously to provide redundant data paths between the hosts and the
drive. However, they can be used to provide failover capability in the event
that communication to the port currently in use is interrupted. This
failover can be accomplished several ways, including:
 Manually disconnect the fiber optic cable from the failed port and
 Connect each port on the drive to a separate Fibre Channel HBA in the
August 2019
Note: Assigning multiple drive exporters to one partition may reduce
the total number of partitions that can be configured in the
library.
connect it to the other port. You may need to reconfigure your host
software to recognize the alternate port.
host. You can also use a dual‐port Fibre Channel HBA. Configure one
HBA (or HBA port) as the primary connection and the other HBA (or
HBA port) as the failover connection. Install failover software on the
host computer to control the transfer of I/O from one HBA to the other
in case of a failure. You may also need to configure your storage
management software to correctly recognize both ports. Refer to your
failover software, HBA, and storage management software
documentation for instructions.
Note: Tape drives sold by Spectra Logic do not support MPIO.
High-Availability Configurations
User Guide—Spectra T950V Library
69