[arch-general] Comment on: Use systemd timers instead of /etc/cron.{hourly, daily, weekly, monthly}?

[Thomas Bächler]

Am 24.04.2014 17:20, schrieb Maciej Puzio:
> I am sorry to say that the decision to replace cron.daily tasks with
> systemd timers is causing problems. After a routine update I noticed
> that my machines now perform daily maintenance tasks exactly at
> midnight. Not only is this time not optimal (too early), but all
> machines perform their maintenance at the same moment, which is far
> from ideal, especially for servers. Previously I had each server to
> perform daily cron jobs at various times, spread between 3 and 6am. On
> my machines this affects updatedb, man-db, logrotate and shadow,
> updatedb generating a lot of I/O and thus being the most problematic.
> I was not able to find any way to configure systemd to fire daily
> calendar timers at a different time of the day (please correct me if I
> missed something). So far I found two workarounds:

This is supposed to be handled by the AccuracySec=, which is supposed to
schedule timers at random times within the specified interval (in our
case, 12h). I have no idea why this doesn't work, it's definitely worth
looking into.

> 1. Override timer files and set OnCalendar with a specific time,
> rather than "daily". This has to be done separately for each timer.

Yes, bad solution. As I said above, we should try to figure out why
AccurarySec= doesn't do anything first.

> 2. Restore cron.daily scripts and mask relevant systemd services and
> timers (i.e. revert the configuration to what it was before the
> update). The resulting config is simpler to manage than the first
> workaround (no separate time settings for each task), so I went with
> this one.

This shouldn't be a permanent solution.


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