Abstract for JES2 Initialization and Tuning Guide · How to send your comments to IBM · Summary How to initialize JES2 in a multi-access SPOOL configuration. JES2 Initialization and Tuning Guide. z/OS JES2 Initialization and Tuning Guide contains the following information in support of JES2 Email Delivery Services. JES2 initialization statement and parameter summary tables · JES2 initialization statement descriptions · APPL(jxxxxxxx) – Application Characteristics.
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Printers pause between data sets. If both checkpoints reside on coupling facilities that become volatile a condition where, if power to the coupling facility initializahion is lost, the data is lostyour data is less secure than when a checkpoint data set resides on DASD.
The 64 KB track size limit is in part due to the limits on allocating a data set extent. In duplex mode, the down-level data set is the duplex or alternate data set. Consequently, concurrent read and write activity are constantly requested to the spool data sets.
z/OS JES2 Initialization and Tuning Guide
Rather than always writing to spool, it simply writes to storage buffers and takes a dump when the JES2 performance issue is encountered. The checkpoint cycle time then refers to the total time it takes for each processor in the complex to obtain ownership of the checkpoint, hold it, and then release control.
To calculate what you are actually realizing, you can use the following command: To do so, you can use the following command: You can store the data in spreadsheet format and portray it graphically to emphasize growth. The LOCKOUT parameter reflects the time between a member being denied access to the shared queues and the time the controlling member is assumed to be down.
This information contains sample application programs in source language, which illustrates programming techniques on various operating platforms.
There are separate JES2 operator commands that the system operator can use to control the spooling subsystem, for example to change what classes of sysout can be sent to a specific printer, or what job classes are to be processed. If output processing overhead is high, it could be because poor work selections are set. In cases such as printers pausing, slow tunlng, or slow initiation of work, it is often lack of access to the checkpoint that is causing the delay.
JES2 uses more giude cycles. Other reasons could be error recovery dump processing or some other type of failure. Checkpoint-related useful time When discussing the JES2 checkpoint cycle, it is important to understand the concept of checkpoint-related useful time. The most obvious example of this situation is a printer. So that methodology was pretty well doomed. Jew2 this instance, WLM takes no action on the image in question. JES2 allocates spool space for a job by dividing each spool volume into track groups.
The following paragraph does not apply to the United Kingdom or any other country where such provisions are inconsistent with local law: Compared to disks — even the slower disks used decades ago — the card readers and line printers were super slow.
Purpose of annd information This information describes JES2 initialization statements and their parameters and provides jss2 charts that highlight details of the statements. You may copy, modify, and distribute these sample programs in any form without payment to IBM, for the purposes of developing, using, marketing or distributing application programs conforming to the application programming interface for the operating platform for which the sample programs are written.
After the queues have been updated to assign an output element to a printer, the printer no longer needs the checkpoint and can obtain the data from the spool even though the checkpoint is owned by another member of the complex. By fencing volumes, you can improve JES2 performance. Each such system has a copy of JES2 running. There are no hard and fast recommendations to follow. These values should be re-evaluated if the JES2 workload is not distributed homogeneously across all the members of the MAS.
However, it gguide be noted that functionality such as parallel access volumes PAV and multiple allegiance MA provide no tning to checkpoint performance due to the locking mechanism that is used to access checkpoint data. Checkpoint allocation summary You can be use the values in Table 1 as starting points for checkpoint allocation. The main benefit of ans is availability. The final write is the same as an intermediate write, but after the final write starts, no further changes to the in-storage queues are allowed.
The more members added to the MAS, the bigger the benefit of initializattion coupling facility structure. The limit on the number of job queue elements JQEs is The checkpoint locking mechanism is used to serialize access when any change is required to the JOB or OUTPUT processes that changes the content of the queues for example, a change in phase or guixe status.
The details of the scheduling form the main point of interest for most of us. It discusses the key components of the JES2 infrastructure in the context of performance goals. This information documents all JES2 initialization statements, in alphabetic order.
To ensure spool space is not wasted, performance is not degraded, and sufficient spool space is catered for, take care with the following parameters of Qnd When large numbers of jobs are awaiting execution, up to five initiators can be started at once. Abbreviated forms of these titles are used throughout this document. The affinity is system based, not job based.
On high use systems, the number of initiators can be reduced while more are started on low use systems. The checkpoint mechanism is as follows: Releases the software lock.
A starting recommendation is to make this 2 to 3 times the desired cycle time or split the difference and do 2. In dual mode, the change log is used, and the 4 KB pages are written only if the change log is filled.
“z/OS V1R JES2 Initialization and Tuning Guide” IBM Library Server
It was okay as a first pass at getting a system to run — way better than an abacus — but that mega bottleneck had to go. It is assumed that readers of this paper have the technical understanding and knowledge to manage an existing JES2 environment. These parameters directly affect the amount of time a system can use to make updates to the queues.
After you have identified the rogue member, you might want to identify in which process PCE it is spending the most time by using the following command: Tuning the checkpoint really starts with getting a good HOLD value for each system. There is a lock table in the coupling facility structure associated with a serialized list.
Processing time The processing time is the amount of time that it takes to perform the mechanical functions of passing the checkpoint among the members in the complex.