Comment by al_borland
2 days ago
What I find interesting is that system services, like Time Machine, don’t prevent sleep… even when Sleep Aid showed at setting where it will wake to back up.
About half the time when I wake my MBP there is a notification waiting for me about Time Machine failing to finish because the system went to sleep. My TM drive is a SSD connected with USB-C. First initial backup took maybe 3-5 minutes. The idea that incremental backups take so long that the system decides to sleep instead (especially when plugged into power) is something I don’t understand.
Now that I’m typing this, I wonder if I have a different issue going on. I moved the drive so it’s plugged into my display. The display powers my laptop and acts as a USB hub. I wonder if the monitor going to sleep is killing power to the drive… but I’d expect an improper ejection notice if that was the case.
I have a similar issue with Time Machine backups. I’ll plug in wall power and a USB drive, do `caffeinate -u -t 7200` or so - and still Time Machine often fails to complete.