Xen users - Dec 2006 - communication between guest OSes n host OS over FC6 with xen

Hi all,
I have a question that how does communication works between guest OS and
host OS over XEN. I mean when i check the hard ware config. over guest OS,
it shows only the size of that VM and all.
But i want to know is it possible to view the hard drive info(like used
space, left space and etc) of host OS through Guest OS. And similarly of
guest OS through Host OS?
Basically how does WMI works on both ?
Thanks
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> -----Original Message-----
> From: xen-users-bounces@lists.xensource.com 
> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of anant
> Sent: 21 December 2006 10:30
> To: xen-users@lists.xensource.com
> Subject: [Xen-users] communication between guest OSes n host 
> OS over FC6 with xen
> 
> 
> Hi all,
> I have a question that how does communication works between 
> guest OS and
> host OS over XEN. I mean when i check the hard ware config. 
> over guest OS,
> it shows only the size of that VM and all.
> But i want to know is it possible to view the hard drive 
> info(like used
> space, left space and etc) of host OS through Guest OS. And 
> similarly of
> guest OS through Host OS?
The GUEST should, by all means, never be able to "know" that
it''s
virtualized. This is part of virtualizations "rules". There''s
been tons
of material written by various people describing how virtualization
should work, and all of those specify that the guest should never be
able to find out that it''s virtualized. 

So the guest should never be able to see the hosts'' hard disk or any
other features of the host.

Of course, if you have a guest that is connected via (virtual) network
to the host system and there''s no network blocking (such as
firewalling), you can use networked tools to find the information you
need - just like if you have two machines sitting next to each other.
[That is EXACTLY what the system should seem like - the virtual machine
should behave exactly like a separate machine that is connected to the
same network as the host]. 
> Basically how does WMI works on both ?
WMI == Windows Management Instrumentation or something else? [That was
the first thing Google came up with]. 

I don''t think WMI in the definition as per above exists in Linux, and
Xen certainly doesn''t have it... 

Your Windows guest will of course be able to use whatever features are
implemented for the drivers that are installed to cope with the emulated
hardware in the guest. If those drivers have WMI, then that''s going to
work just like if you had a motherboard based on the PIIX chipset, a WDC
disk, a RTL8139, Intel whatever it is or Ne2K network device, etc, etc.
There should be no visible difference (aside from the time it takes to
perform some operations - which may vary in either direction) between
the REAL and Virtual system. 


--
Mats



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On Thu, 2006-12-21 at 02:29 -0800, anant wrote:
> Hi all,
> I have a question that how does communication works between guest OS and
> host OS over XEN. I mean when i check the hard ware config. over guest OS,
> it shows only the size of that VM and all.
> But i want to know is it possible to view the hard drive info(like used
> space, left space and etc) of host OS through Guest OS. And similarly of
> guest OS through Host OS?
> Basically how does WMI works on both ?
> Thanks
You''ll need to use something like snmp, or (preferably) something
lighter if you want to poll and refresh frequently. 

Part of the beauty of Xen is that each guest is oblivious to other
guests, including the guest with privileges to query the hypervisor for
the limited statistics available (dom-0).

I found that using Lighttpd + ssl on an odd port displaying the output
of something like this :

http://dev1.netkinetics.net/xmlpulse/

is rather effective, and very easy to parse into any kind of graphical
display. 

If you give me a few more weeks, I''ll have the info that you see in
xentop also included in that feed.. I''m just playing around with the
best way to structure the xml and switches to "shape" what is
displayed
and how.

Best,
-Tim


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hi 
So you mean Simple Network Management Protocol...well if i download this
tool over guest OS would it be able to retrieve info of host OS.
And similarly like if i have 10 guest OS running and i want to know the
hardware config of each of them. Logging on to each of them would be a bit
problem. Well through dom0 if its possible to view win32 BIOS, WIN 32 base
port, hard disk etc..of all the guests OS then it would be great ease.Pls
let me know about it. 
If i install WMI over guest, so my question becomes what information would i
get out of that. Would that be able to  communicate with Host OS or not....?







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> -----Original Message-----
> From: xen-users-bounces@lists.xensource.com 
> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of anant
> Sent: 21 December 2006 12:52
> To: xen-users@lists.xensource.com
> Subject: Re: [Xen-users] communication between guest OSes n 
> host OS over FC6 with xen
> 
> 
> hi 
> So you mean Simple Network Management Protocol...well if i 
> download this
> tool over guest OS would it be able to retrieve info of host OS.
> And similarly like if i have 10 guest OS running and i want 
> to know the
> hardware config of each of them. Logging on to each of them 
> would be a bit
> problem. Well through dom0 if its possible to view win32 
> BIOS, WIN 32 base
> port, hard disk etc..of all the guests OS then it would be 
> great ease.Pls
> let me know about it. 
> If i install WMI over guest, so my question becomes what 
> information would i
> get out of that. Would that be able to  communicate with Host 
> OS or not....?
The answer is that you need to do EXACTLY the same thing as you would do
when you have a set of ten machines networked together, and you have a
Linux server thatyou want to use as a monitoring station. The only
difference is that physically, you only have ONE machine and no cables
connecting the machines. From a software standpoint tho'',
there''s no
difference. 

Whether you use SNMP or some other monitoring technology depends mostly
on:
1. What you want to achieve.
2. What''s avaialble for your guest OS. 

--
Mats
> 
> 
> 
> 
> 
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> OS-over-FC6-with-xen-tf2864764.html#a8007395
> Sent from the Xen - User mailing list archive at Nabble.com.
> 
> 
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