Re: [PATCH] xenctld - a control channel multiplexing daemon

[Anthony Liguori <anthony@codemonkey.ws>]

Daniel Stekloff wrote:

>Can't we add functionality in Xen to make domain id's unique? When
>creating a new domain, the management tools can query the running (or
>even suspended) domains and find a unique domain id to use. I think you
>can tag a domains with their state. 
>
>  
>
Yes, I think eventually domains have to have some sort of UUID.  I'm not 
convinced that those can't be mapped onto the current domain ids by 
configuration tools though.

Here's a few scenarios to consider:

1) Someone suspends domain A to disk.  Domain A continues to run.  
Without stopping the original instance of Domain A, they start up the 
suspended image.

2) Someone takes the suspended form of Domain A and transfers it to 
another machine.  They start it up while Domain A is still running on 
another machine (creating a resource conflict).  If you're using DHCP, 
VMware can handle this scenario gracefully btw.

Are these errors?  I think it can be argued either way.

>I disagree. If we're to consider the larger management world, we need to
>lay the groundwork for managing domains now. I think the questions
>aren't easily answered, but I believe they should be. If we don't
>implement everything to start, we should at least have an idea where
>we're going. 
>  
>
I completely agree that we need to lay a groundwork.  I think 
large-scale domain management tools our outside the scope of the current 
focus.  What I'd like to see is an architecture that's good enough that 
when these large-scale domain management tools are finally worked out 
they can just be plugged in without rewriting the Xen management 
infrastructure.

I think the key to this is to keep things as simple as possible.  Don't 
require configuration files, don't rely on any sort of internal database 
for persistent state.

BTW, this discussion is great.  I'm very interested to see what others 
think of the broader management picture.

Regards,

-- 
Anthony Liguori
anthony@codemonkey.ws



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