[systemd-devel] Halt then reboot

[Che]

I wonder if it's possible to discuss matters, in any list, without
everything coming out looking like an insult and/or a put-down...
:/



On Sun, Sep 18, 2016 at 3:17 PM, Dark Penguin <darkpenguin at yandex.ru> wrote:

> 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
>
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>
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