HP StorageWorks Secure Path V3.0C for Linux and Linux Workgroup Edition Installation and Reference Guide (AA-RU7VD-TE, February 2004)

Secure Path Technology
24 Secure Path v3.0C for Linux and Linux Workgroup Edition Installation and Reference Guide
Secure Path operation
Path failover occurs automatically when a selected set of error conditions is
detected. Secure Path normally performs path failover only when user I/O is
active or if path verification is enabled. However, it is possible for Secure Path
Manager 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.
For the HSG80, EVA5000, and EVA3000, 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:
When a failure occurs, Secure Path marks the affected path as Failed. This
removes it from the list of usable paths for the storageset.
— If no Active paths remain for the device, Secure Path activates an
Available path on the same controller, if one exists.
— If no Available paths remain on the same controller, Secure Path attempts
to move the device to a Standby path on the other controller.
Restore options
Secure Path lets you set the path Restore option to Manual or Automatic.
■ In Manual mode, you must enter a management utility command to restore
devices to their preferred path. The operation is performed even if system I/O
is in process to the selected device.
■ In Automatic mode, Secure Path tests a failed path at fixed intervals if I/O is
in process for the affected device. If the path appears to be viable, and the path
is set as Preferred, the path state is set to Active and I/O will again be routed
through this path.