[ncolug] Re: vm
- From: "Chuck Stickelman" <CStickelman@xxxxxxxx>
- To: <ncolug@xxxxxxxxxxxxx>
- Date: Fri, 23 Nov 2007 10:28:11 -0500
Writing a program that sends a SIGHUP to another process upon a specific event
id trivial. I'm not programmer butr I could do it in a BASAH script.
From trhe hypervisor's point of view they are Linux apps and therefore should
behaive as such. Linux apps should behaive properly when they catch a signal.
The shell-script that was posted earlier effectively does just that.
The good would be that the guest OS would initiate a shutdown upon seeing the
SIGHUP from the Hypervisor... Sems pretty useful to me...
Chuck
-----Original Message-----
From: "larry" <larry@xxxxxxxxxxxx>
To: "ncolug@xxxxxxxxxxxxx" <ncolug@xxxxxxxxxxxxx>
Sent: 11/23/2007 9:40 AM
Subject: [ncolug] Re: vm
I am quite sure I am missing things, the point of your message being
only one of many... that is why I am running this by you all.
1.) no one has verified that any hypervisor is ABLE to send a SIGHUP in
response to an external event
2.) they are *not* "after all, Linux apps" - they are instances of
operating systems
3.) if it did send it, what good would that do for a Windows guest? Or a
MAC OS guest?
Chuck Stickelman wrote:
> Larry, I think you mised the point of my prevoius message...
>
> The guests *should* shut down cleanly when the Hypervisor sends them a
> SIGHUP. (...regardless of why the Hypervisor sends the signal...) Sending a
> SIGHUP to the guest VM *should* be the same as choosing to shut it down from
> inside the VM...
>
> They are, afterall, just Linux apps...
>
> Of couse the UPS doesn't send the SIGHUP that's the job of the Linux
> Hypervisor. Which is the best choice for monitoring the UPS... Though some
> UPS monitoring applications have LAN awareness and can push the UPS status
> out to multiple systems - both Physical and Virtual...
>
> Chuck
>
>
> -----Original Message-----
> From: "larry" <larry@xxxxxxxxxxxx>
> To: "ncolug@xxxxxxxxxxxxx" <ncolug@xxxxxxxxxxxxx>
> Sent: 11/22/2007 10:32 PM
> Subject: [ncolug] Re: vm
>
> No, the guests do NOT "shut down cleanly" just because you stopped or
> shut down the hypervisor.
>
> You want to talk about "standards" in regard to UPS signaling
> behaviour?! Which of the dozen or so standards would you like to discuss?
>
> Mike wrote:
>
>> Chuck Stickelman wrote:
>>
>>> So what I hear you say is:
>>> Hook the UPS to the physical machine
>>> Have the host OS monitor the UPS's state
>>> When the UPS signals the host it sends a SIGHUP to the Virtual Machines
>>> The VMs should then interpret the SIGHUP as a Shutdown command
>>>
>>> Is that what you had in mnd?
>>>
>>> Does anyone know if that's how it works?
>>>
>>> Chuck
>>>
>> Yes.
>>
>> The signal may depend on the VM design though. I would hope they have
>> used enough sense to honor some standard.
>>
>> This really is a near trivial problem. The guests shutdown cleanly
>> during a normal shutdown, yes? Why should a shutdown instituted by
>> UPS software or even admin written (monitoring) scripts be any different?
>>
>> Mike
>>
>> To unsubscribe send to ncolug-request@xxxxxxxxxxxxx with 'unsubscribe'
>> in the Subject field.
>>
>>
>>
>
>
--
"Perception is strong and sight weak. In strategy it is
important to see distant things as if they were close and
to take a distanced view of close things."
Miyamoto Musashi (1584-1645)
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