CHECKPOINT command

Summary

Privileges

Any user can issue a CHECKPOINT command without arguments; a system manager or the operator at the console can issue a CHECKPOINT command with arguments. A system administrator may be able to issue a CHECKPOINT command with certain arguments, dependent upon the setting of the CHKPRIV parameter.

Function

Requests that Model 204 perform a checkpoint

Syntax

CHECKPOINT [TRAN | SUBTRAN | ABORT | MESSAGE] [[SET | UNSET | END] EXTENDED QUIESCE]]

Usage notes

The CHECKPOINT command requests that a checkpoint be performed. The Model 204 checkpoint facility provides a means of recovering a valid copy of a database in case of a system failure. The checkpoint facility operates by logging images of any changed file pages to a checkpoint data set.

When a checkpoint is performed, updating is temporarily suspended, the database is brought to a valid state, and marker records are written on the data set. If a subsequent system crash occurs, the database can be rolled back in time to its status at the time of a previous checkpoint. For a detailed explanation of check pointing and system recovery, refer to the Model 204 System Manager's Guide.

When a CHECKPOINT command is executed, Model 204 does not close any currently open files or groups. Model 204 automatically generates a unique identifier to be associated with the checkpoint.

After the checkpoint has been performed successfully, Model 204 informs the operator and the audit trail of the date and time that the checkpoint was completed.

The security required for the ABORT and MESSAGE keywords is the same as for the CHKABORT and the CHKMSG commands.

When a CHECKPOINT command with an END, SET, or UNSET keyword is issued in a valid context, the following message is displayed:

M204.2611: CHECKPOINT SET/UNSET/END COMMAND SUCCESSFUL

When a CHECKPOINT command with a SET, UNSET, or END keyword is issued in an invalid context, the following message is displayed:

M204.2612: CHECKPOINT SET/UNSET/END COMMAND UNSUCCESSFUL - reason