[ncolug] Re: vm

  • From: larry <larry@xxxxxxxxxxxx>
  • To: ncolug@xxxxxxxxxxxxx
  • Date: Fri, 23 Nov 2007 10:47:27 -0500

Can you back up your statement that an instance of Windows NT appears to the hypervisor to be a Linux app? Even id the hypervisor is a Windows application? Doesn't make sense to me.


I stand by my statement that a SIGHUP is meaningless to any OS other than Linux.

Chuck Stickelman wrote:
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

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