7.10.4 Changing the shared resource configuration while hosts and servers are running

Adding and deleting shared resources while hosts and servers are running is called dynamically changing the shared resources. This subsection explains how to dynamically change the shared resources.

The method depends on the type of shared resource. To add and delete shared disks dynamically, you use the command for dynamically changing a server's shared resources (mondevice command). To add and delete LANs, you edit the LAN status settings file.

You can use the command for dynamically changing a server's shared resources (mondevice command) in either the active or the standby system.

To add and delete shared resources by using the command for dynamically changing a server's shared resources (mondevice command):

1. Make sure that the active and standby servers have completed their startup processing.

   Execute the server and host status display command (monshow command) to verify that ONL is displayed for the active server and SBY is displayed for the standby server.

2. Connect or disconnect the shared resources.

   Execute the command for dynamically changing a server's shared resources (mondevice command) to connect new shared resources or to disconnect existing shared resources. The server environment definitions for the active and standby servers that are sharing the resources are changed according to the results of the change made to the shared resources.

3. Check the new settings after change.

   Use the server and host status display command (monshow -d command) to verify that the shared resources have been changed as specified.

When you execute the command for dynamically changing a server's shared resources (mondevice command), the server environment definitions for the active and standby servers that are sharing the resources are changed automatically as appropriate for the change made to the shared resources. After you have changed the shared resources dynamically, you must also verify that the server environment definitions have been changed correctly.

If the shared resources for the active server cannot be changed, HA Monitor will not change the shared resources for the standby server. If the shared resources for the standby server cannot be changed, HA Monitor changes only the shared resources for the active server. In such a case, the settings for the shared resources will no longer match between the active and standby servers. To synchronize the settings for the shared resources, you will have to terminate the standby server, synchronize the contents of the server environment definitions between the active and standby servers, and then restart the standby server.

If the shared resources cannot be changed by using the command for dynamically changing a server's shared resources (mondevice command), possible reasons include HA Monitor errors, conflicting command specifications, and the following:

When the command for dynamically changing server's shared resources (mondevice command) is executed on the active server:

• The active server has not finished its startup processing.

• A server failure occurred on the active server.

• A communication error occurred when notifying the standby server of the change (the shared resources for the standby server cannot be changed).

When the command for dynamically changing a server's shared resources (mondevice command) is executed on the standby server:

• The active or standby server has not finished its startup processing.

• A server failure occurred on the active or standby server.

• A communication error occurred when notifying the active server of the change to the shared resources or when receiving notification of completion of the change to the shared resources from the active server (the shared resources for the active server cannot be changed).

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