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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However, by looking at external processes, you can make judgements regarding JES2 performance and its ability to get to the checkpoint data set. Example 2 uses the output from Example 1.
Rather than always writing to spool, it simply writes to storage buffers and takes a dump when the JES2 performance issue is encountered. A summary of the displays is as follows: The limit on the number of job queue elements JQEs is These values should be re-evaluated if the JES2 workload is not distributed homogeneously across all the members of the MAS. Standard JES2 processing allows the allocation of track groups across any available spool volume. Preliminary to that, we might want to know a little about the basic pieces jees2.
This information describes JES2 initialization statements and their parameters and provides summary charts that highlight details of the statements. The intermediate write activity updates the in-storage queues with new changes from the system and brings the DASD copy up to tunig.
When using this command to display information pertaining to a large range of jobs, started tasks or TSO users. If the HOLD parameter is set lower than the time it takes for the primary write to 2 JES2 Performance and Availability Considerations complete, the hold time is extended until the primary write completes.
Sample JES2 initialization data set
Think of the checkpoint as tunint two states: There is spool sharing. 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. If you are experiencing delays in jobs getting to execution, this trace can help identify the cause of the delays.
Both types of initiators can coexist. If it must take two cycles, then je2s can take two or more seconds to complete and can write twice as much data to the checkpoint.
Your site can define how many jobs of the same class are allowed to run concurrently, and the scheduling selection priority of each class relative to each other class. ENG Sarah L.
Any functionally equivalent product, program, or service that does not infringe any IBM intellectual property right may be used instead. You can use the following tools for analysis of performance-related data. The content provides guidelines but does not offer clear cut recommendations. The holding area is called spool space.
So, why not guidd the HOLD value very small so that no member keeps the checkpoint longer than necessary? Complex useful time During a checkpoint cycle it is important to ensure that some member of the complex is using it. The JES2 health monitor is intended to address situations where JES2 is not responding to commands and where it is not possible to determine the issue.
To identify the most active member or members, the simplest approach iniyialization to establish which has the most checkpoint activity locks.
The checkpoint mechanism is as snd After JES2 reads a job into the system, JES2 writes the job, its job control language, its control statements, and its data to a spool data set until further processing can occur.
A track group consists of one or more DASD tracks.
CONTENTS “OS/ V2R JES2 Initialization and Tuning Guide” IBM Library Server
As the checkpoint data set is frequently referenced, particularly in MAS configurations, it should not reside on any initializzation that contains high-usage data sets. On very early mainframe computers, the system read input jobs from a punched card reader, one line at a time, one line from each punched card. All commands that have the JES2 command prefix followed by a J are sent to the monitor command subtask.
RMF Coupling Facility report for analysis of delays when the checkpoint is resident on a coupling facility. Because spool volumes are read by a number of vendor products including Aneany change to how spool addressing operates affects these products. When large numbers of jobs are awaiting execution, up to five initiators can be started at once.
IBM z/OS MVS mainframe overview of JES2 Archives – Ask the z/OS Lady
However, in some cases, jfs2 the checkpoint is held long enough, the process can be done in one checkpoint cycle. There is a set of very JCL-like control statements you can use to specify your requirements to the spooling subsystem. This information contains examples of data and reports used in daily business operations.
This paper discusses JES2 processor utilization, checkpoint and spool considerations, workload manager WLM managed initiators, scalability, command processing, and identifying issues with performance degradation. 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.
Frequently, run system jobs can be isolated on separate volumes leaving jnitialization remaining volumes to be exploited by user-defined work. In dual mode, the change log is used, and the 4 KB pages are written only if the change log is filled. With multiple spool devices, they should target different channels and control units on separate channels.