Planning critical jobs

Planning critical jobs.

Workload service assurance provides the means to identify critical jobs, define deadlines, and calculate timings for all jobs that must precede the critical job.

If it is critical that a job must be completed before a specific time, you can flag it as critical when you add it to a job stream using the Workload Designer functions on the Dynamic Workload Console. You can define the deadline either at job or job stream level.

Jobs can also be flagged as critical by including the critical key word on the job statement when you create or modify a job stream using the composer command line.

When you run the command to include the new job in the production plan, all jobs that are direct or indirect predecessors of the critical job are identified. These jobs, together with the critical job itself, form a critical network.

Because timing of jobs in the critical network must be tightly controlled, Time Planner calculates the following timing benchmarks for each critical network job:
Critical start
Applies to distributed systems only and represents the latest time at which the job can start without causing the critical job to miss its deadline.
Critical start times are calculated starting with the deadline set for the critical job and working backwards using the estimated duration of each job to determine its critical start time. For example, if the critical job deadline is 19:00 and the estimated duration of the critical job is 30 minutes, the critical job will not finish by the deadline unless it starts by 18:30. If the immediate predecessor of the critical job has an estimated duration of 20 minutes, it must start at latest by 18.10.
Note: Only the deadline of the critical job is considered when calculating critical start times for jobs in the critical network. If other jobs have deadlines defined, their critical start times might be later than their deadlines.
Earliest start
Represents the earliest time at which a job in the critical network can start, taking into consideration all dependencies and resource requirements.

Estimated start times are calculated starting with the earliest time at which the first job or jobs in the critical network can start and working forward using the estimated duration of each job to estimate the start time of the job that follows it.

Estimated start and end time
For the initial calculations, these values are set to the planned start and end time. They are subsequently recalculated to take into consideration any changes or delays in the plan.
Estimated duration
The estimated duration of a job is based on statistics collected from previous runs of the job. If the job has never run before, a default value of one minute is used. Take this into account when considering the accuracy of calculated timings for critical job networks that include jobs running for the first time.

The timings for each job in the critical network are added to the Symphony file, which includes all the plan information and is distributed to all workstations on which jobs are to be run.

As the plan is run, Plan Monitor monitors all critical networks: subsequent changes to the critical network that affect the timing of jobs trigger the recalculation of the critical and estimated start times. Changes might include manual changes, for example, releasing dependencies or rerunning jobs, and changes made automatically by the system in response to a potential or actual risk to the timely completion of the critical job.

Specific views for critical jobs and their predecessors, available from the Dynamic Workload Console, allow you to keep track of the processing of the critical network. The views can immediately identify problems in your planning of the critical job. For example, if the estimated start time of a job in the critical network is later than the critical start time, this is immediately signaled as a potential risk to the critical job.