[systemd-devel] Restart instantiated services after suspend

[Marcos Felipe Rasia de Mello]

2013/11/20 Lennart Poettering <lennart at poettering.net>:
> On Tue, 19.11.13 14:18, Marcos Felipe Rasia de Mello (marcosfrm at gmail.com) wrote:
>
>> Hi folks,
>>
>> I am trying to disable HDDs power management in a systemd way (aka no
>> shell scripts :)
>>
>> /etc/udev/rules.d/99-hdparm.rules
>>
>> SUBSYSTEM=="block", KERNEL=="sd*", ATTR{removable}=="0",
>> TAG+="systemd", ENV{SYSTEMD_WANTS}+="hdparm@%k.service"
>
> Why do you do this asyncrhonously via a systemd service? Given that this
> tool runs and terminates quickly invokign this with RUN inside of the
> udev rule itself sounds like the best approach.
>

If suspend/resume did not reset HDD power setting, sure, better run
hdparm directly from the udev rule.

My initial idea was rerun hdparm@ transient units after suspend with
something like what you have suggested:

mkdir /etc/systemd/system/sleep.target.wants
ln -s /etc/systemd/system/hdparm at .service
/etc/systemd/system/sleep.target.wants/

but it did not work so here I am. :)

>> It works fine, but after the machine wakes up from suspend, I need
>> that all hdparm at .service be run again. Is there a way to accomplish
>> this?
>
> Well, you could drop in a service into sleep.target.wants/ which orders
> itself after systemd-suspend.service...
>