The switch processing procedure ensures that an application switches over to another node in the cluster.
Switch requests are divided as follows:
Priority switch request
RMS identifies the target node according to the node priority list defined during the configuration process.
Directed switch request
The user specifies the target node.
The types of switches are divided as follows:
Switchover
The application running on a node is to be switched over to another node.
Switch-online
An application that is not running on any node is started; or the node on which it has previously been running has failed.
Point
During switch processing, RMS notifies all the nodes in the cluster of the procedure. This prevents competing requests.
Example 8
The scenario for this example is as follows:
app is online on fuji2RMS.
The system administrator sends a directed switch request on fuji3RMS with the aim of switching app to fuji3RMS.
Switch processing is as follows:
RMS forwards the switch request to fuji2RMS because fuji2RMS is the online node of the userApplication object.
app on fuji2RMS notifies the corresponding nodes in the cluster (in this case, app on fuji3RMS) that switchover processing is active. This means that competing activities are blocked.
app on fuji2RMS sends a request to app on fuji3RMS to establish whether any faults are known in the local graph on fuji3RMS. In this example, there are no known faults in the local graph on fuji3RMS.
app on fuji2RMS commences offline processing.
As soon as RMS has successfully deconfigured app on fuji2RMS, app on fuji2RMS notifies all corresponding nodes in the cluster that the application will now be running on fuji3RMS. Blocking of competing requests is simultaneously cancelled.
app on fuji2RMS terminates its activity by sending an explicit online request to app on fuji3RMS.
app on fuji3RMS commences online processing.
