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The concept of DomU.
Hello,
The Guest OS means DomU, but each guest has a separate DomU? For example, When Xen running 100 guest operating systems then it has 100 DomUs?

Thanks.
Re: The concept of DomU. [ In reply to ]
You should make use of the resources that are freely available, for
example https://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide
(which I found by googling "xen guest domain"). From that guide:

Guest virtual machines running on a Xen Project Hypervisor are known as
“domains”. A special domain known as domain0 (or dom0) is responsible
for controlling the hypervisor and starting other guest operating
systems. These other guest operating systems are called domUs. This is
because these domains are “unprivileged” in the sense they cannot
control the hypervisor or start/stop other domains.

In short, the answer to your question is Yes.

On 8/22/2020 7:51 PM, Jason Long wrote:
> Hello,
> The Guest OS means DomU, but each guest has a separate DomU? For example, When Xen running 100 guest operating systems then it has 100 DomUs?
>
> Thanks.
>
Re: The concept of DomU. [ In reply to ]
Thank you.Thus, the number of DomU is equal to the number of quest OS.

Sent from Yahoo Mail on Android

On Sun, Aug 23, 2020 at 7:18 AM, Bernd Bausch<berndbausch@gmail.com> wrote: You should make use of the resources that are freely available, for
example https://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide
(which I found by googling "xen guest domain"). From that guide:

Guest virtual machines running on a Xen Project Hypervisor are known as
“domains”. A special domain known as domain0 (or dom0) is responsible
for controlling the hypervisor and starting other guest operating
systems. These other guest operating systems are called domUs. This is
because these domains are “unprivileged” in the sense they cannot
control the hypervisor or start/stop other domains.

In short, the answer to your question is Yes.

On 8/22/2020 7:51 PM, Jason Long wrote:
> Hello,
> The Guest OS means DomU, but each guest has a separate DomU? For example, When Xen running 100 guest operating systems then it has 100 DomUs?
>
> Thanks.
>
Re: The concept of DomU. [ In reply to ]
Hello,

On Sun, Aug 23, 2020 at 02:52:45AM +0000, Jason Long wrote:
> Thus, the number of DomU is equal to the number of quest OS.

No. You don't appear to have read what Bernd wrote nor read the link
that Bernd gave you.

To restate:

Guests on Xen are called domains. A domU is an unprivileged domain.
There are other domains which are privileged, and most installs have
at least one, referred to as a "dom0", that has privileges to
control the hypervisor and access real hardware, That dom0 is still
a domain, or a guest if you want to use that terminology.

So almost all Xen installs will have more domains than domUs,
because "domU" is a subset of "domain" and most installs require a
dom0 as well. dom0 is still a domain, or "a guest" if you like.

Cheers,
Andy
Re: The concept of DomU. [ In reply to ]
Excuse me, Xen Project running 100 guest OSes. How many DomU running?






On Sunday, August 23, 2020, 11:37:26 AM GMT+4:30, Andy Smith <andy@strugglers.net> wrote:





Hello,

On Sun, Aug 23, 2020 at 02:52:45AM +0000, Jason Long wrote:
> Thus, the number of DomU is equal to the number of quest OS.


No. You don't appear to have read what Bernd wrote nor read the link
that Bernd gave you.

To restate:

Guests on Xen are called domains. A domU is an unprivileged domain.
There are other domains which are privileged, and most installs have
at least one, referred to as a "dom0", that has privileges to
control the hypervisor and access real hardware, That dom0 is still
a domain, or a guest if you want to use that terminology.

So almost all Xen installs will have more domains than domUs,
because "domU" is a subset of "domain" and most installs require a
dom0 as well. dom0 is still a domain, or "a guest" if you like.

Cheers,
Andy
Re: The concept of DomU. [ In reply to ]
Hello,

On Sun, Aug 23, 2020 at 07:14:14AM +0000, Jason Long wrote:
> Excuse me, Xen Project running 100 guest OSes. How many DomU running?

In the usual case, at most 99. What is not clear about this?
Without understanding where you aren't following all I can do is
repeat what Bernd and I have already typed.

A Xen system normally requests a dom0, which is a domain; it is a
guest, it runs a guest OS like Linux or NetBSD.

Your question as posed says only "guests", which in Xen terminology
is "domain", and dom0 is a domain. So with 100 domains, on most Xen
setups that would mean 99 domU and 1 dom0.

However it seems like what you really meant is, "100 unprivileged
domains". Since a domU is an unprivileged domain that question reads
as "I'm running 100 domUs. How many domUs am I running?"

The thing you are maybe not getting is that dom0 is a guest, like
all the other guests, except that it has extra privileges. It is
still a virtualized OS like all the other ones on the hypervisor.

Cheers,
Andy
Re: The concept of DomU. [ In reply to ]
On Sun, Aug 23, 2020 at 07:23:41AM +0000, Andy Smith wrote:
> A Xen system normally requests a dom0, which is a domain; it is a
^^^^^^^^^^requires
> guest, it runs a guest OS like Linux or NetBSD.
Re: The concept of DomU. [ In reply to ]
Well, my explanation was sloppy, thanks for setting it straight Andy.
With the definition guest=domain, a Xen hypervisor with 100 guests has
one dom0 and 99 domU's. If you define guest as "a virtual machine that
does not control the hypervisor", 100 guests means 100 domU's.

On 8/23/2020 4:25 PM, Andy Smith wrote:
> On Sun, Aug 23, 2020 at 07:23:41AM +0000, Andy Smith wrote:
>> A Xen system normally requests a dom0, which is a domain; it is a
> ^^^^^^^^^^requires
>> guest, it runs a guest OS like Linux or NetBSD.
Re: The concept of DomU. [ In reply to ]
Thank you so much.






On Sunday, August 23, 2020, 05:01:34 PM GMT+4:30, Bernd Bausch <berndbausch@gmail.com> wrote:





Well, my explanation was sloppy, thanks for setting it straight Andy.
With the definition guest=domain, a Xen hypervisor with 100 guests has
one dom0 and 99 domU's. If you define guest as "a virtual machine that
does not control the hypervisor", 100 guests means 100 domU's.

On 8/23/2020 4:25 PM, Andy Smith wrote:
> On Sun, Aug 23, 2020 at 07:23:41AM +0000, Andy Smith wrote:
>> A Xen system normally requests a dom0, which is a domain; it is a
>                        ^^^^^^^^^^requires
>> guest, it runs a guest OS like Linux or NetBSD.