Installation and Reference Guide HP StorageWorks Secure Path 3.0F Service Pack 4 for HP-UX 11i v1.0 and 11i v2.0 (5697-8001, March 2009)

• Active-Active — In the Active-Active model, I/O processing may be routed through both controllers
simultaneously, providing better performance in addition to high availability.
NOTE:
Secure Path automatically retries I/O requests that terminate in error due to ownership transfers.
Active-Passive disk arrays also queues new I/O requests until the ownership transfer has completed
to ensure data integrity.
Path definition
Within Secure Path, a path is defined as the collection (configuration) of physical interconnect
components including HBAs, switches, RAID controllers, and the ports on the controllers. Because the
Secure Path driver component is positioned between the HBA driver and the system SCSI disk driver,
the Secure Path driver distinguishes the physical paths when elements of the SCSI equivalent address
are different.
Some configurations include multiple switches within a fabric, with the switches connected by one or
more interswitch links. Secure Path cannot detect these paths and cannot manage them. While these
interswitch paths provide an additional level of redundancy within the fabric, their management is
handled directly within the switch. Refer to the documentation received with your switch hardware
for more information about interswitch link routing and failover policies.
Secure Path automatically sets the path state and reflects the status of the current active path. Because
of path failures, the currently active path may be different from what you expect. See Table 7 for a
list and description of path states.
Secure Path operation
This section describes the following:
• Failback options
• Load balancing
• Path verification
Path failover occurs automatically when a selected set of error conditions is detected. Secure Path
normally performs path failover only when your I/O is active or you have enabled the path verification.
However, it is possible for spmgr to show some units with a common failed path in the failover state,
while other units remain accessible through that path. Units remain in the failed path if there is no
I/O or until they are polled.
Failover follows a hierarchy, conditioned by the state of load balancing, as described below. Secure
Path does not change the mode of preferred paths in failover situations, so you can restore original
path assignments after making repairs.
• Load balancing disabled
When a failure occurs, Secure Path marks the path failed and switches to the next available path
connected to the same controller, if there is one.
If there is no available path on the same controller, Secure Path attempts to move the device to a
standby path on the other controller.
• Load balancing enabled
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