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CA7 – LEAD TIME CONCEPT (LOOK BACK ISSUE)
Lead Time is the period (in hours)[time-window], that a job looks back in time, to check if all its requirements(promises) are fulfilled. See the below example. Here, my job MYJOBONE has a requirement on LEADJOB1, with a Lead Time of 5 hours.
JOB=MYJOBONE LIST=RQMT
NAME ID MEMBER -NAME- -ID -ID- DSNBR DSNBR STP DDS RUNS DATE/TIME
JOB=LEADJOB1 SCHID=000 VRSN=10176/1131 LEADTM=05
Suppose, my job MYJOBONE is a scheduled job, it is scanned out every day, and enters the REQ (Request) Queue at 07:00 AM in the mornings. Now, the MYJ* Job is going to check for its requirement of LEAD* job. Has the LEAD* Job completed in the last 5 hours? Thus, the MYJ* Job searches for its requirement LEAD* job’s completion in the time-window of 02:00 AM to 07:00 AM. If the LEAD* Job would have completed in the time-frame [02:00-07:00 AM], the requirement is satisfied.
However, if the LEAD* Job completes, say at 00:00 Hrs, this doesn’t fall in the time-window 02:00-07:00 AM, so the requirement shall not be satisfied. The MYJ* Job merely keeps waiting in REQ (Request) Queue (even though the LEAD* Job ran, but ran at 00:00 Hrs). This is a classic example of a Look-back Issue.
Very often, there is too large a time-gap that elapses between a predecessor job A’s completion, and its dependent B’s starting out. When B is brought into the REQ (Request) Queue, if A’s completion doesn’t fall in the Look-back (Lead-time) window, B keeps waiting in the REQ Queue. These are called Look-back Issues. CA-7 Look-back issues generally happen in the Production Environment, generally due to delays in Batch Cycle, holidays etc.
Lead-Time could take several values.
Values are the following:
00 – Specifies that the predecessor job must have started and completed successfully since the last run of the dependent job.
NN – Specifies that since the last run of this job, the predecessor job has started and completed successfully within the last NN hours.
Values for NN can be 1 to 98.
99 – Specifies that the requirement is never considered initially satisfied when this job enters the request queue. The dependent job must complete normally while this job is in the request queue
(NOTE: HHMM – 0030 can be used for 30 Minutes.)
Courtesy: Content is taken from
http://www.mainframes360.com/2010/07/ca-7-commands.html
And
http://ca7jobs.blogspot.in/
As the explanation was clearly mentioned in the above blogs, I just took that information.
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