IBM Z Workload Scheduler, IWS and DWC
IBM's scheduler family has two members. IBM Z Workload Scheduler — still widely called TWSz or OPC — schedules mainframe batch. IBM Workload Scheduler (IWS) schedules distributed systems. The Dynamic Workload Console (DWC) is the web interface for both.
Names you will hear
| Name | Means |
|---|---|
| OPC, TWS for z/OS, TWSz, IZWS | IBM Z Workload Scheduler, the mainframe scheduler |
| TWS, Maestro, IWS | IBM Workload Scheduler for distributed systems |
| DWC | Dynamic Workload Console, the browser interface for both |
TWSz: how it is organised
- Controller — the brain, running on z/OS, holding the plans and databases.
- Tracker — runs on each z/OS system, submits jobs and reports their events back.
- Application description (AD) — a group of operations (jobs) with their dependencies and run cycles.
- Workstations — where operations run: a z/OS system (CPU), a manual task, a printer, or a distributed agent.
- Special resources — limits such as 'only one job may update this database at a time'.
Long-term plan and current plan
The long-term plan (LTP) works out which applications run on which days, often weeks ahead. Each day a batch job extends the current plan (CP), the live list of operations for the next period. Operators work in the current plan.
| Status | Meaning |
|---|---|
| W | Waiting for predecessors or resources |
| A | Arriving — waiting for its start time |
| R | Ready to run |
| S | Started |
| C | Complete |
| E | Ended in error |
IWS on distributed systems
IWS uses job streams containing jobs. A master domain manager builds the daily production plan, called the Symphony file, with the JnextPlan process and sends it to fault-tolerant agents, which can keep running even if they lose contact with the master. The conman command line controls the plan.
$ conman "sj PAYHOST#PAYROLL.@" # show jobs in a job stream $ conman "ss @#@" # show all job streams $ conman "rerun PAYHOST#PAYROLL.LOADTXN"
The Dynamic Workload Console
DWC gives one browser view of both TWSz and IWS: monitor jobs, browse output, rerun from a failed step, and edit definitions. Many sites use it instead of the older ISPF dialogs.
Common mistakes
Changes to application descriptions usually reach the current plan only when the plan is next extended. For tonight, modify the current plan as well, through change control.
TWSz supports restart and cleanup from a chosen step. Restarting from the top may repeat work or fail on datasets that already exist.
If a tracker is down, jobs may run but their completion is not reported, so successors wait. Check the tracker before blaming the job.
What you will see at work
- Many mainframe shops still call TWSz 'OPC' after its original name.
- You may use ISPF dialogs on z/OS during the night and DWC from your laptop during the day — same plan, different windows.
- Cross-platform dependencies are common: a z/OS job waits for an IWS job on a Linux server, or the other way round.
Key terms
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