Failover function
HP 3PAR Cluster Extension Software requires cluster software to automatically fail over among systems on a local site or between sites. Because the software manipulates the application startup process before storage system virtual volumes are accessed, it must be integrated as the first resource (in the order of resources). The software must be installed on all servers in the cluster that can run the application service.
How HP 3PAR Cluster Extension utilizes virtual volumes
To write to HP 3PAR Remote Copy paired virtual volumes, you must ensure that the paired virtual volumes are in read/write mode. Volume group members (paired virtual volumes) are in read/write mode on the source (primary) virtual volume only. The destination (secondary) virtual volume is in
•In case of a failover, HP 3PAR Cluster Extension Software automatically changes the direction of the mirrored pair. A reboot of the server is not necessary.
•In case of a disaster, the storage system can have several different states for volume group members. HP 3PAR Cluster Extension Software determines whether those virtual volumes can be accessed and made available to the application service.
How HP 3PAR Cluster Extension stores information
HP 3PAR Cluster Extension stores information about the application environment in an internal object database and uses HP 3PAR InForm CLI to gather information about the state of the associated volume group members. Information about the configured storage system environment and failover behavior is transferred either directly by the cluster software or by gathering it from the user configuration file. An internal object database provides the software with the format and default value of supported parameters.
Virtual volume states are stored in the internal object database, which uses a rule engine to process those states. The rule engine matches current volume group member states and configuration parameters with a defined rule, stores it in the database, and invokes predefined actions. Those actions prepare the volume group member virtual volumes to be enabled for access or stop the application service startup process if the matching rule requires a stop.
General installation prerequisites
This section describes general installation prerequisites for HP 3PAR Cluster Extension.
Ensure that the following conditions are met before installing HP 3PAR Cluster Extension Software:
•HP Remote Copy links (including extender hardware) are redundant and bidirectional.
•Alternate I/O paths (network and storage links) between servers and the HP 3PAR storage system are set up.
•Cluster and client networks are redundant.
•Cluster nodes can communicate with each other.
•The latest supported software and firmware versions, fixes, FC adapter firmware, and driver versions for your servers and HP 3PAR storage systems are installed.
•The cluster nodes in your zoning configuration each recognize their respective (local) HP 3PAR storage system, but not the remote HP 3PAR storage system.
Disk space and system memory requirements
•50 MB for the HP 3PAR Cluster Extension installation directory (%ProgramFiles%\Hewlett- Packard\Cluster Extension 3PAR)
•At least 25 MB of system memory
6Preparing to install HP 3PAR Cluster Extension