[plug] ups driven automatic server shutdown

[Daniel Pittman]

"Patrick Coleman" <blinken at gmail.com> writes:
> On 6/19/08, Adam Hewitt <ahewitt at theozhewitts.com> wrote:
>> Hi All,
>>
>> I am currently trying to find a good solution for the above problem. So far
>> all the options I have are either a lot of development or dont go far enough
>> into what I need.
>
> Yeah, I've thought the same thing when I was looking something for
> about 40 servers earlier this year. I didn't look into nut in depth,
> though, and chances are it'll do what I want based on what I've seen
> here (I dont -really- have any ordering requirements across servers
> when shutting down, beyond the obvious PDC, file servers).

Mmm.  For what it is worth, one bit of advice I can give y'all from
painful personal experience is that engineering your systems to avoid
this sort of ordering constraint.

If you do have constraints on shutdown order, and they do cause you
grief, then I guarantee that they will be violated: if not by
accidentally getting the order wrong, then hardware failure will
eventually take down your system.


Building an environment that is robust against unordered shutdown makes
it more robust against unexpected failures, and more able to survive
when the inevitable march of entropy bites you.

> A centralised UPS shutdown manager with ordering and constraints
> sounds like the job for a quick Python project :)

It may /sound/ easy, but it actually isn't as trivial as you might
hope.  The biggest problem you will face is distributed error recovery,
I suspect, where state isn't exactly what you expect.

Regards,
        Daniel