Using the IBC Messaging Command-Line Utility

The vxibc command-line utility enables you to perform the following IBC Messaging tasks:

• Registering an Application Name
• Displaying the Registered Application Name for an RVG
• Receiving an IBC Message
• Sending an IBC Message
• Unfreezing the Secondary RVG
• Unregistering an Application Name
• Receiving and Processing an IBC Message Using a Single Command
• Sending and Processing an IBC Message Using a Single Command

For details on using the vxibc command and the available options, see the online manual pages.

Registering an Application Name

Before being able to perform IBC operations on an RVG, you must register an application name for the RVG. The sender and the receivers of the IBC message must register the same application name. Multiple application names (up to a maximum of 32) can be registered for an RVG. Registration is not persistent through host reboots. Applications on rebooted hosts must be reregistered.

To register an application name for an RVG:

Displaying the Registered Application Name for an RVG

You can use the vxibc status command to display the currently registered application names for a Replicated Volume Group (RVG).

To display the registered application names for an RVG:

Receiving an IBC Message

You can use the vxibc receive command to receive the IBC message sent from the Primary to a Secondary.

To receive an IBC Message:

Note that the application_name for the Secondary RVG must have been previously registered.

When the Secondary receives the IBC message, the state of the data volumes on the Secondary is the same as the state of the data volumes on the Primary at the time the IBC message was inserted in the replication stream. Subsequent writes are delivered to the Secondary and stored in the SRL, that is, replication is frozen. Secondary replication remains frozen until an unfreeze operation is performed, or the specified freeze_timeout expires. The default behavior for the receive operation is to block until an IBC message is received. The option -n makes the receive operation non-blocking, and returns if there is no message to receive. If the operation succeeds, the received message is displayed; if a file name is specified the message is written to that file.

Sending an IBC Message

You can use the vxibc send command to send an IBC message from the Primary to a Secondary.

To send an IBC message:

Note that the application_name for the Primary RVG must be previously registered.

The IBC message is inserted into the update stream of the specified RLINKs. If an RLINK is not specified, the message is sent to all RLINKs currently attached to the Primary RVG.

IBC messages are always sent to the Secondary RVG irrespective of whether or not the application_name is registered on the Secondary.

If the application is registered on the Secondary, then the IBC message is discarded on the Secondary if a receive operation is not performed within the deliver-timeout period.

In the case the application is not registered at the Secondary, then the IBC message is held for ten minutes before being discarded. If the application_name is registered within this time, then the IBC message is discarded if a receive operation is not performed within the deliver-timeout period. On the Secondary, the RVG remains frozen until an unfreeze operation is performed or the specified freeze_timeout expires.

Unfreezing the Secondary RVG

The vxibc unfreeze command unfreezes the Secondary RVG. This operation must be performed after receiving the IBC message using the receive operation.

To unfreeze an IBC message:

The vxibc unfreeze command permits replication to continue by allowing updates that were performed on the Primary data volumes after the send operation was executed on the Primary RLINK, to be applied to the Secondary RVG.

Unregistering an Application Name

The vxibc unregister command unregisters an application name for the RVG.

To unregister an application name:

The application name must have been previously registered for the RVG. Further send operations against the application name are not possible after unregistering on the Primary RVG.

You can unregister the application on the Secondary if the following conditions are met:

• If the IBC message has arrived on the Secondary and has been received by the user.
• If the IBC message has arrived on the Secondary and not received by the user, but the delivery timeout period has expired.

If you used the vxibc regrecv command, you do not have to unregister the application.

Receiving and Processing an IBC Message Using a Single Command

The vxibc regrecv command enables you to specify a command to be performed on the arrival of the IBC together with the command arguments. The vxibc regrecv command performs the following operations in a single step:

• Registers the application name
• Receives the IBC message
• Runs the specified command with the provided arguments
• Unfreezes the Secondary RVG
• Unregisters the application name.

To receive and process an IBC message in a single step:

Sending and Processing an IBC Message Using a Single Command

The vxibc regsend command performs the following operations in a single step:

• Registers the application name
• Sends the IBC message
• Unregisters the application name

The vxibc regrecv command must be started on the Secondary host before
the IBC message sent from the Primary host gets invalidated due to a delivery timeout on the Secondary. This can also be done by first executing the vxibc regsend command on the Primary, followed by the vxibc regrecv command on the Secondary within the delivery time-out period which is by default 600 seconds. Otherwise, the IBC message is discarded on the Secondary because there is no corresponding registered application name.

To send and process an IBC message in a single step:

The vxibc regrecv command must be issued before the IBC message delivery times out at the Secondary. Typically, this command is issued before the IBC is sent from the Primary.