TLOG-DEQUEUE Command

The TLOG-DEQUEUE command starts the transaction logging process.

Format

TLOG-DEQUEUE [(options)]

Parameter(s)

options	The following options are supported:
	D	Causes transactions to be dequeued immediately after they are queued.
	E	Terminates transaction logging when the queue is empty.
	I	Causes the tape buffer to be written to the tape device.
	O	Logs off the transaction logger when it is finished dequeueing transactions to backup medium.
	S	Suppresses session-number and transaction-number in the “in process” output display.

Description

The transaction logger is an independent process that functions something like the Spooler. Transaction logging dequeues all current update transactions which have been stored by the update logger and writes them to backup medium. Since the transaction logger is independent of the update logger that enqueues the transactions, it can be started and stopped before, during, or after the actual enqueueing of any transactions.

Rocket recommends that TLOG-DEQUEUE be run on a phantom process. Only one process at a time can be designated as the transaction logger. If you try to start a transaction logging process while another one is running, an error message displays.

Using TLOG-DEQUEUE

To use TLOG-DEQUEUE:

Load a backup medium into the drive before you enter TLOG-DEQUEUE.
Type TLOG-DEQUEUE. The backup medium is attached and a start-of-session segment is output to backup, followed by the transactions from the transaction queue.

Use :ULOG-ON to start update logging.
Use TLOG-SUSPEND to temporarily stop a transaction logging session.
Use TLOG-STOP to terminate a transaction logging process.

There are five options available with the TLOG-DEQUEUE command:

The D option specifies that transactions be dequeued immediately after they are queued. Normally dequeueing is delayed in order not to affect the process doing the updating and queueing.
The E (empty) option causes the transaction logging session to terminate as soon as the queue is empty. If the queue is empty to begin with, no transaction logging session is started.
Normally, the dequeuer waits until the tape buffer is filled to flush it out to the selected tape device. If there are entries that have already been copied to the tape buffer, and the queue becomes empty, the I (purge buffer) option causes the tape buffer to be written to the tape device. This prevents items from sitting in the tape buffer too long. This is particularly useful for mvBase if the selected tape device is a virtual tape link.
The O (off) option logs the transaction logging process off whenever the session normally terminates. This includes terminations caused by pressing BREAK and typing END.
The S (suppress) option suppresses the session-number and transaction-number in the “in process” output display.