IBM Tivoli Workload Scheduler


IBM Workload Scheduler is a software that plans, executes and tracks jobs on several platforms and environments. Its main purpose is to manage the computing resources on collections of computers to allow different users to efficiently share these resources to run parallel programs.
It comprises two products:
Plus some ancillary applications
Products can be integrated to schedule and monitor from a single point of control with the use of a Java console called JSC or in the latest versions with a web based user interface called TDWC.
Workload Scheduler for z/OS was originally produced in the 1970s by IBM's Nordic Laboratory in Lidingo, Sweden where it was known as OPC, which stands for "Operations Planning and Control". In 1989 the name was changed to Operations Planning and Control/Advanced when many advanced features were added and the product has remained very much the same ever since. The name changed again to Operations Planning and Control/ESA when later adapted to work in a Sysplex Environment. After IBM bought the Tivoli company and OPC came under Tivoli's umbrella it was briefly renamed TME/10, then to Tivoli Workload Scheduler, but as Tivoli had previously renamed Maestro to Tivoli Workload Scheduler OPC was renamed Tivoli Workload Scheduler for z/OS. However, the name Operations Planning and Control continued to appear on the primary option panel and elsewhere until Version 8 Release 5. The TWSz version numbers jumped from Version 3 to Version 8 to align with TWSd.
Workload Scheduler was originally produced by Unison Software where it was known as Maestro. Maestro was bought by the Tivoli company when they realised the need for a Unix scheduler. It was renamed Tivoli Workload Scheduler. IBM bought the Tivoli company and gave it the responsibility for systems management, both distributed and mainframe. Tivoli at first decided to drop OPC and, because Maestro had an agent that ran on z/OS, get OPC customers to migrate to Maestro. When it became obvious that Maestro couldn't replace OPC, Tivoli brought OPC under the Tivoli Workload Scheduler name. Many of the OPC concepts were ported to Maestro.
In 1988, users of OPC together with support from IBM, established ASAP - TWS Education + Training - a volunteer, user supported, not-for-profit organization which is managed by a volunteer board of directors and administered by MeetingWorks, LLC of New London, CT.

Workload Scheduler for z/OS

Workload Scheduler for z/OS runs on IBM Z Systems' primary operating system, z/OS. TWSz schedules and runs work on multiple platforms, both mainframe and distributed. TWSz comprises a z/OS started task known as a Controller and programs known as Tracker-Agents running on every machine under its control.
The Controller's databases hold details of the work to run, the scheduling instructions and information about resources and restrictions. The databases provide input to the Long Term Plan which is a calculation of when work will run in the future. A second plan, the Current Plan, uses the Long Term Plan as input to determine which jobs it should include and expands that with information from the databases. The Current Plan is a detailed production schedule. Current Plan will submit jobs when precessors are complete and resources are available.
The Tracker-Agent, which is a z/OS started task or a program running on Unix, Windows, HP-UX, or any other operating system, communicates with the Controller to feedback information about jobs starting and ending. The Controller uses that information to update its Current Plan, changing statuses and submitting jobs as their predecessors finish.
The Controller can replace the TWS Distributed Master Domain Manager and control a distributed network of Maestro Agents by generating and propagating the Maestro Symphony file. This is known as End-To-End Scheduling.
Communication with TWSz is via a set of supplied and customisable ISPF panels. There have been limited function graphical user interfaces available for more than a decade, the latest is the Web browser based Tivoli Dynamic Workload Console. The TDWC doesn't supply all the functions available with the ISPF interface which is need to browse and modify the Long Term Plan, run maintenance batch jobs, rerun old jobs from the DB2 repository, run audit trail reports and access Service Functions.
LoadLeveler is a job scheduler written by IBM, to control scheduling of batch jobs. LoadLeveler matches the job requirements with the best available computer resource for execution. It was primarily available only for AIX operating system, however it is now also available for POWER and x86 architecture Linux systems.
LoadLeveler has been moved under the Tivoli Software brand as of version 3.3.2 in April 2006, and has been renamed to Tivoli Workload Scheduler LoadLeveler.