Automating the Backup Process

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Automating the Backup Process

Exploiting DCMT QUIESCE

Backing up a database while the DC/UCF system is active can be automated through the use of the DCMT QUIESCE command. To assist in this effort, the following can be specified as options:

A unique identifier for use in subsequent DCMT DISPLAY ID and DCMT VARY ID commands to query or terminate an outstanding quiesce operation.
The action that should be taken in the event that a quiesce point cannot be reached within a specified time interval. The available choices are to abandon the quiesce operation or force the quiesce by canceling conflicting tasks.
An indication of whether a new archive journal file should be created when the quiesce point is reached.
An indication of whether update activity in the target areas should be restarted automatically once the areas are quiesced.

Quiesce User Exit

When a quiesce point is achieved, numbered exit, Exit 38 is invoked. This exit can be used to initiate the next step in the backup process. For example, it can submit a job to the internal reader, thus enabling the QUIESCE task to automatically initiate a copy operation. Once the files are copied, a subsequent UCF batch job step can invoke further system tasks to complete the backup process.

Rather than submitting a batch job, exit 38 might instead use an API to directly interface to a "zero-time copy" facility if the database resides on a storage device that provides such a capability.

More Information

For more information about how to code an Exit 38 routine, see the CA IDMS System Operations Guide.
For more information about the DCMT QUIESCE command, see the CA IDMS System Tasks and Operator Commands Guide.

Automating a Quiesced Backup

The following illustrates how the DCMT QUIESCE command can be used to automate a quiesced backup operation.

Activity	Description
dcmt quiesce dbname CUST hold swap CUSTBKP	This command initiates a quiesce operation identified as CUSTBKP. All areas in all segments included in the database name CUST will be quiesced. When the quiesce point is reached, a new archive journal file will be created and exit 38 will be invoked. The quiesce point will be held until the quiesce operation is explicitly terminated.
Exit 38 is invoked	Exit 38 submits a batch job through the internal reader (or an equivalent mechanism) to initiate the copy operation.
Batch job is executed	The batch job first copies all files containing areas of the CUST database and then invokes a UCF batch job step that terminates the quiesce operation by issuing a DCMT VARY ID command.
dcmt vary id CUSTBKP terminate	This command terminates the quiesce operation and makes the CUST areas available for update.

Automating a Hot Backup

The following illustrates how the DCMT QUIESCE command can be used to automate a hot backup operation.

Activity	Description
dcmt quiesce dbname CUST nohold swap CUSTBKP1	This command initiates a quiesce operation identified as CUSTBKP1. All areas in all segments included in the database name CUST will be quiesced. When the quiesce point is reached, a new archive journal file will be created and exit 38 will be invoked. The quiesce operation will then terminate and make the areas available for update.
Exit 38 is invoked	Exit 38 submits a batch job through the internal reader (or an equivalent facility depending on the operating system) to initiate the copy operation.
Batch job is executed	The batch job first copies all files containing areas of the CUST database and then invokes a UCF batch job step. The UCF batch job step either initiates a second quiesce operation by issuing a DCMT QUIESCE command or forces a new archive journal file to be created by issuing a DCMT VARY JOURNAL command.
dcmt quiesce dbname CUST nohold swap CUSTBKP2	This command initiates a quiesce operation identified as CUSTBKP2. All areas in all segments included in the database name CUST will be quiesced. When the quiesce point is reached, a new archive journal file will be created and exit 38 will be invoked. The quiesce operation will then terminate and make the areas available for update. Exit 38 examines the quiesce identifier and determines that no further action is needed.
dcmt vary journal	This command forces the use of another disk journal file which in turn causes a batch execution of the ARCHIVE JOURNAL utility statement. Note: Automatic submission of the ARCHIVE JOURNAL job is dependent on the implementation of a site-specific means (such as WTOEXIT) to examine console messages and use operating system facilities to submit a batch job.