Job-tracking data sets (EQQJTARC, EQQJTnn, EQQDLnn)

Job-tracking data sets are a log of updates to the current plan. They optionally contain audit trail records. Job-tracking data sets comprise:
  • Job-tracking logs (EQQJTnn)
  • Dual job-tracking logs (EQQDLnn)
  • Job-tracking archive (EQQJTARC)

You must allocate EQQJTARC and at least two job-tracking logs (EQQJT01 and EQQJT02) for a Z controller. The actual number of JT logs that you should allocate is determined by the value that you specify on the JTLOGS keyword of the JTOPTS initialization statement. If you decide to allocate three job-tracking logs, specify the DD names EQQJT01, EQQJT02, and EQQJT03. If you specified EQQJT01, EQQJT02, and EQQJT04, an error occurs and IBM Z Workload Scheduler terminates. IBM Z Workload Scheduler uses the job-tracking logs in turn. When a current plan backup is performed, the active log is appended to EQQJTARC data set.

The size of the CP files, JT and JTARC, can become large, but with appropriate tuning of the size and of the DP frequency, they will not allocate additional extents. If necessary, use the allocation of additional extents (not additional volumes, because only extent allocation is supported in the shipped JT allocation samples). The JTLOG keyword default defines five job-tracking logs. It is recommended that you specify at least three job-tracking logs. Job-tracking logs are switched at every current plan backup. If the interval between backups is very low and JTLOGS(2) is specified, the previously used job-tracking log might not have been archived before IBM Z Workload Scheduler must switch again. If it cannot switch successfully, the normal-mode-manager (NMM) subtask is automatically shut down, preventing further updates to the current plan.

You can optionally allocate dual JT logs. These logs are identified by the EQQDLnn DD names in the Z controller started-task JCL. Allocate the same number of dual JT logs as JT logs. The numeric suffixes, nn, must be the same as for the JT logs, because IBM Z Workload Scheduler uses the logs with the same number: EQQJT01 and EQQDL01, EQQJT02 and EQQDL02, and so on. IBM Z Workload Scheduler writes job-tracking information to both logs, so that if the active JT log is lost it can be restored from the dual log, and IBM Z Workload Scheduler can be restarted without losing any events. To achieve the maximum benefit from dual JT logs, you should allocate them:
  • With the same attributes as the JT logs
  • With at least the same amount of space as the JT logs
  • On alternate I/O paths and physical volumes than their corresponding JT logs
IBM Z Workload Scheduler tries to use dual JT logs if you specify DUAL(YES) on the JTOPTS initialization statement of a Z controller.

The job-tracking-archive data set accumulates all job-tracking data between successive creations of a new current plan (NCP). Therefore, allocate EQQJTARC with enough space for all job-tracking records that are created between daily planning jobs; that is, extend or replan of the current plan. In other words, be sure that you allocate for EQQJTARC an equal or greater amount of space than the total of the space you allocate for the JT files, or you will get a system error. When the daily planning batch job is run, the active job-tracking log is appended to EQQJTARC, and the JT log is switched. The archive log, EQQJTARC, is then copied to the track log data set referenced by the EQQTROUT DD name during the daily planning process. When IBM Z Workload Scheduler takes over the NCP, the archive data set is emptied.

For a detailed description of the IBM Z Workload Scheduler recovery procedures that use the job-tracking data sets, see Customization and Tuning.