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.
JES2 Performance and Availability Considerations 19 Because the primary concern is performance issues, the number of requests, the source address space, and the time to complete the requests are usually the first indicators of a problem.
Sample JES2 initialization data set
As the checkpoint data set is frequently referenced, particularly in MAS configurations, it should not reside on any volume that contains high-usage data sets. In such cases, commands respond quickly, printers pick up work sooner, and so forth. A starting recommendation is to make this 2 to 3 times the desired cycle time or split the difference and do 2.
Many sysout files are initialkzation really printed, but are viewed and further processed directly from the spool space initkalization TSO using a software product like SDSF.
However, even in these circumstances, the impact is minimal. From the perspective of a single member in a complex, checkpoint-related useful time is the time in a checkpoint cycle, which starts at the beginning of the primary write and ends at the beginning of the final write. Remote job entry lines time out. Because spool volumes are read by a number of vendor products including SDSFany change to how spool addressing operates affects these products. Jobs take longer to run.
“z/OS V1R JES2 Initialization and Tuning Guide” IBM Library Server
Such jobs can receive space from more volumes than if the job spends its life on a single system. Checkpoint-related non-useful time is composed of all other portions of tuninng checkpoint cycle, namely the time it takes to perform Read1 and Read2 functions and to complete the final write. This time is primarily a function of the amount of time to do DASD reads and writes of the checkpoint data set information.
The furnishing of this document does not give you any license to these patents. Use caution with this command because it provides a significant amount of spooled output. However, it initiakization provide useful information that you can use in performance analysis.
RMF Coupling Facility report for analysis of delays when the checkpoint is resident on a coupling facility. It wrote printed output to a line printer, one line at a time. Just because one member is unable to access the queues another member might be performing useful work. JES2 uses the coupling facility lock to serialize access to the checkpoint data set.
z/OS JES2 Initialization and Tuning Reference
JES2 is still a single extent data set and has a very low read-to-write ratio. Service class goals are missed Tuningg system is under utilized and there are jobs waiting to be selected Jobs have an affinity to a system on which no initiator is available Decision factors are: New initiators are started in circumstances such as the following: The 64 KB track size limit is in part due to the limits on znd a data set extent.
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 SPOOLDEF: This information documents all JES2 initialization statements, in alphabetic order. It is assumed that readers of this paper have the technical understanding guice knowledge to manage an existing JES2 environment. It is a controlled environment where each member is allowed limited and regulated data set access. So, you can run them with confidence.
This information could include technical inaccuracies or typographical errors. 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. Information concerning non-IBM products was obtained from the suppliers of those products, their published announcements or other abd available sources.
Whether an RMF report shows the checkpoint as performing well is often immaterial to actual delays that are caused by waiting for access to the checkpoint. When using this command to display information pertaining to a large range of jobs, started tasks or TSO users. In general, this process takes two checkpoint cycles to complete.
Red books JES2 Performance and Availability Considerations
Duplex mode must always be established when using a coupling facility structure. TSO logons are delayed. Optimizing response time This approach is for installations where some JES2 functions have a need of a response time smaller than the cycle time.
Abbreviated forms of these titles are used throughout this document. The following paragraph does not apply to the United Kingdom or any other country where such provisions are inconsistent with local law: If one particular PCE is shown to be far busier than others, then you can balance the associated work across more members of the MAS to spread out the activity.
There is spool sharing. It facilitates the split of a large DASD spool pool into smaller pools for critical systems. IBM, therefore, cannot guarantee or imply reliability, serviceability, or function of these programs.
Spool partitioning Spool partitioning or fencing allows track group allocation across explicit volumes. Many JES2 processes involve updating checkpoint control blocks, then writing data to spool, and then making final updates to checkpoint control blocks. There are no hard and fast recommendations to follow. It also provides a mechanism to have spool space online and ready to use if spool volumes start to fill up.
The idea for this post came from a suggestion by Ian Watson. Any references in this information to non-IBM Web sites are provided for convenience only and do not in any manner serve as an anx of those Web sites.
Specifically, JES2 supports both relative and absolute track addressing for spool. A general recommendation is to work towards a cycle time of around two seconds.