Understanding Queuing

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HP OpenVMS System Manager's Manual, Volume 1:...

Setting Up and Maintaining Queues

Designing Queue Environments

Understanding Queuing

A batch or print job submitted either by entering the DCL command SUBMIT or PRINT or through an application is sent to a queue for processing. Information about the user's queue request, including the type of job, the file name or names, the name of the queue, and any special options, is sent to the queue manager. The queue manager stores and retrieves appropriate information from the queue database to print or execute the job.

The queue manager places the job in the appropriate queue to await its turn for processing. Only one print job can be printed on a printer at a single time. However, more than one batch job can execute simultaneously in a batch queue.

For more information about the queue manager and queue database, and the operation of batch and print queues, including print symbionts, see Managing the Queue Manager and Queue Database.

Managing Queues on Small Systems

Many features available for queues are not required on small systems with minimal queuing needs (for example, on workstations). If you are managing a small system, you probably need only the information in the following sections:

Topic Section

Simple batch queue configuration
Using a Simple Batch Queue Configuration

Simple output queue configuration
Using a Simple Output Queue Configuration

Setting up and starting queues
Planning Your Queue Setup

Choosing and specifying queue options
Using Queue Options

Managing queues
Using Queue Management Commands

Managing jobs in queues
Managing Jobs in Queues

Topic	Section
Simple batch queue configuration	Using a Simple Batch Queue Configuration
Simple output queue configuration	Using a Simple Output Queue Configuration
Setting up and starting queues	Planning Your Queue Setup
Choosing and specifying queue options	Using Queue Options
Managing queues	Using Queue Management Commands
Managing jobs in queues	Managing Jobs in Queues

Understanding Classes and Types of Queues

In general, queues can be divided into two classes:

Class Description

Execution queues
Queues that accept batch or print jobs for processing.

Generic queues
Queues that hold jobs until an appropriate execution queue becomes available. The queue manager then requeues the job to the available execution queue.

Class	Description
Execution queues	Queues that accept batch or print jobs for processing.
Generic queues	Queues that hold jobs until an appropriate execution queue becomes available. The queue manager then requeues the job to the available execution queue.

The following sections provide more details about execution and generic queues.

Execution Queues

Descriptions of types of execution queues follow:

Batch execution queues accept only batch jobs. A batch job executes as a detached process that sequentially runs one or more command procedures. The user defines the list of command procedures when submitting the job.

Output execution queues accept jobs that a symbiont processes. The queue manager sends the symbiont a list of files, which the user defines when submitting the job. An output symbiont transfers data from a disk to an output device. As the symbiont processes each file, it produces output for the device it controls, such as a printer or a terminal.

The operating system provides a standard print symbiont named PRTSMB, which prints files on hardcopy devices. The LAT print symbiont LATSYM prints files on output devices attached to LAT ports. You can also design symbionts for this or any other file-processing activity that the OpenVMS batch and print queuing system manages. (Refer to the OpenVMS Utility Routines Manual for more information.)

Output execution queues include the following types:

Type Description

Printer execution queue
Uses a symbiont to direct output to a printer.

Terminal execution queue
Uses a symbiont to direct output to a terminal printer.

Server execution queue
Uses a user-modified or user-written symbiont to process the files that belong to jobs in the queue.

Type	Description
Printer execution queue	Uses a symbiont to direct output to a printer.
Terminal execution queue	Uses a symbiont to direct output to a terminal printer.
Server execution queue	Uses a user-modified or user-written symbiont to process the files that belong to jobs in the queue.

When you create an output execution queue, you designate it as either a printer, a terminal, or a server execution queue; you can also specify the symbiont to be associated with the queue. However, when the queue is started, the symbiont process associated with the queue can override the queue designation if the queue type specified does not match the type of device.

The standard symbiont provided with the operating system determines whether it is controlling a printer or a terminal. The symbiont communicates this information to the queue manager, which, if necessary, changes the type designation of the output execution queue. By convention, a user-written or user-modified symbiont that does not deliver output to a printer defines its queue as a server queue.

Generic Queues

Descriptions of types of generic queues follow:

Generic batch queues direct jobs only to batch execution queues. Generic batch queues are typically used in OpenVMS Cluster environments to distribute the batch work load across several nodes (see Using Generic Batch Queues in an OpenVMS Cluster Environment).

Generic batch queues are not automatically stopped when a node shuts down. Therefore, they do not need to be started when a node reboots.

Generic output queues direct jobs to any of the three types of output execution queues: print, terminal, or server. Generic output queues are typically used to distribute the output work load among several like printers (see Using Generic Output Queues).

Generic output queues are not automatically stopped when a node shuts down. Therefore, they do not need to be started when a node reboots.

Logical queues are a special type of generic output queue that transfers jobs to another output execution queue. You might use a logical queue to temporarily redirect a queue when the device on which it runs is broken.

A logical queue transfers its jobs into the execution queue specified with the ASSIGN/QUEUE command. For information about setting up a logical queue, see Assigning a Logical Queue.

Understanding Autostart Queues

HP recommends that you use autostart queues whenever possible for a variety of reasons. Autostart queues simplify startup and ensure high availability of execution queues, allowing you to perform the following tasks:

With a single command, start all autostart queues on a node

Specify a list of nodes (in an OpenVMS Cluster environment) to which a queue can automatically attempt to fail over

Autostart failover is particularly useful on LAT queues. Because LAT printers are usually shared among users of multiple systems or OpenVMS Cluster systems, many users are affected if a LAT queue is unavailable. For highest availability, set up your LAT queues with a list of nodes to which the queue can fail over, so the queue can continue to run even if a node becomes unavailable.

To use autostart queues, you must perform the following three steps:

Task Description

1
Create the queue as an autostart queue and, optionally, specify a failover list.

2
Activate the queue for autostart. You can do this either when you create a queue, or after you create one.

3
Enable autostart on a node. You can do this before or after you create a queue.

When you enable autostart on a node, the queue manager automatically starts all stopped, active autostart queues capable of running on the node. Any autostart queue that fails over to the node is also automatically started.

Task	Description
1	Create the queue as an autostart queue and, optionally, specify a failover list.
2	Activate the queue for autostart. You can do this either when you create a queue, or after you create one.
3	Enable autostart on a node. You can do this before or after you create a queue. When you enable autostart on a node, the queue manager automatically starts all stopped, active autostart queues capable of running on the node. Any autostart queue that fails over to the node is also automatically started.

Planning Your Queue Setup explains these steps in detail.

Designing Queue Environments