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

Secure Path Technology
25Secure Path v3.0C for Linux and Linux Workgroup Edition Installation and Reference Guide
Load balancing
Secure Path supports the Load Balancing attribute. When enabled, Load
Balancing allows multiple paths between a host and a specific storageset to be
used in a round robin fashion. Using multiple paths spreads the load across all
components in the RAID storage system.
Load Balancing may not be used in environments that use device reservations as a
lock mechanism because the RAID array controllers enforce reservations on a
per-port basis.
Load Balancing requires a Fibre Channel configuration that results in at least two
paths per controller from the host node to the storage system. While this can be
accomplished with several different physical configurations, maximum
performance potential is achieved when all ports of the RAID storage system are
used.
When Load Balancing is enabled, the Secure Path driver causes all paths to the
owning controller to be marked Active by default. This is true when the following
conditions occur:
■ A host boots up
■ Secure Path fails over a storageset from one controller to the other
■ For the EVA3000/EVA5000 or HSG80, you can manually move a selected
storageset between controllers using the Secure Path management utility,
spmgr.
Path verification
When enabled with spmgr, Path Verification causes Secure Path to periodically
test the status of all paths to all storagesets and marks them Available, Failed,
Active, or Standby. Path Verification does not test paths that are in a Quiesced
state.
Path verification is useful for detecting failures that affect overall path
redundancy, before they affect failover capability. If an Active path fails path
verification, failover occurs. If a path fails path verification, its state will change
from Available to Failed.
If a path marked Failed passes path verification, the path state is set to Available if
it is on the Active controller and Standby if it is on the Standby controller. If
Auto-Restore is enabled, the path becomes Active only if the path is on the Active
controller and it is marked Preferred.