[systemd-devel] Halt then reboot

[Dark Penguin]

>>>> Now that systemd manages the shutdown procedure, I don't know if it's
>>>> possible to achieve the same behaviour (and thus make NUT work with
>>>> systemd).
>>>
>>> As already mentioned, it is ouside of scope of OS actually. How you did
>>> it before systemd?
>>
>> It was actually a feature of NUT - and a default and recommended feature
>> at some moment.
>> See this, from their FAQ:
>> http://networkupstools.org/docs/FAQ.html#_i_8217_m_facing_a_power_race
>> And this - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=835634
>> (there is a link to an old discussion about implementing this feature).
>> Now it doesn't work anymore, and I'm trying to find a new solution...
>
> So you do not even bother to describe how it worked before so others may
> suggest how it can be (re-)implemented using systemd? Oh, well ...

No, that's not what I meant! Instead of trying to describe it myself, 
I've posted a link to their website where they describe the procedure 
first-hand! Basically, there is a "shutdown script" (though I'm not 
exactly sure where is it), which is apparently executed right before 
halting, so you can put "sleep" and "reboot" there. I was wondering if 
there is a similar thing in systemd.


>>> systemd supports switching back to initramfs instead of directly halting
>>> system. This allows you to implement your logic there after everything
>>> is completely shut down and unmounted (you probably need to unmount old
>>> root manually though). You can even monitor UPS from initramfs and only
>>> reboot when it reports power is back to make it safe.
>>
>> This may be the best idea without touching the kernel. But it still
>> can't go through the "proper" halt procedure with syncing and unloading
>> the drives, correct?..
>
> I have no idea what "unloading the drives" means.

That's why I've posted the second link: in that bug discussion, one 
person is explaining why this is a bad idea. In general, only the kernel 
can do "proper" halt, which among other things includes unloading the 
heads from the hard drive so that it is ready to be powered off (and 
apparently "hdparm -y" does not cut it somehow).


-- 
darkpenguin