Scheduling background activities like making backups has moved from cron to launchd, and now to a more complex system. This has reduced the reliability of macOS and made it harder to support.
Automatic backups will still become irregular or fail altogether, making Sierra 10.12.6 unsuitable for servers and systems requiring sustained operation.
How to diagnose this bug, manage it when it occurs, and try to prevent it from happening: latest information.
Lack of sleep can do strange things to people. Perhaps it can to Macs too. Could this solve the Time Machine irregularity bug?
Sleep interrupts the scheduling and dispatch of background tasks. Here’s how it looks in the dispatching systems.
Time Machine backups are but one of 70-80 background services which are run by macOS dispatching systems. Here’s a list of some of the others.
When scheduled backups become irregular or stop, this affects much more than just Time Machine. This is what happens, and why you must restart.
How scheduling concurrent and background tasks using XPC Activity works, and compares with alternatives such as NSBackgroundActivityScheduler.
Trying to get a more coherent overview of the different paths to concurrent, asynchronous, and background task management in macOS. Draft for discussion.
When part of the mechanism which schedules and dispatches Time Machine backups fails, those backups become irregular. Here it is shown in a clear diagram.