Xen users - Jan 2009 - I need help with fully utilizing xen on a new system

Hello xen list.  I am an absolute novice with Xen, having never been 
able to set it up despite my several trials.  I have built a new, modern 
system (last computer was seven years ago) with the hardware 
virtualization technologies so I''m hoping to be able to run Windows 
natively along side a graphical Linux desktop.

Here is what I was imagining ...

Dom0 = Gentoo
DomU = Gentoo w/gui
DomU = Ubuntu
DomU = Windows XP
DomU = Windows 2000
DomU = Windows 98
DomU = FreeBSD (multiple versions)

My hardware is dual quad core Xeon processors with 8 GB of RAM and 
several hard drives in a RAID 6 array.

1) Is it better to have the "drives" that are exported to the DomUs be
partitions, files, LVM, etc.?

2) If somebody has a computer running Xen and a Microsoft and Linux OS, 
how does one switch control between them?

3) Does every component of the system need to be understood by the Dom0 
to be able to be utilized by a DomU?

4) If the Dom0 is x64, can a DomU be 32 bit?

5) If the answer to 4 is yes, then can that DomU then be migrated to a 
Xen computer with a Dom0 that is 32 bit?

6) Does the Dom0 need to statically partition the resources (RAM, CPU) 
to the DomUs, or is there a dynamic, kernel / Xen controlled allocation 
that is possible?

Thanks for reading.  Let me know if I clarify anything.  I''ve tried to 
be vague because I do not really know much at all about Xen.  I don''t 
know what''s important to state or what is inconsequential 
I''ve read the
official "Xen 3.0 Documentation" PDF from xen.org, but I have a
feeling
that it is outdated, because I remember that being about the same as 
what I read years ago.

-Charles

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I''ll try to address your last question about documentation: Yes it is
old,
but someone is revising it as we speak. The pdf describes Xen 3.0.
However, if you look at the html version instead, it''s on Xen 3.3. In
the
appendix in particular, HVM is described, which is exactly what you need
for your Windows domU:s.

Cheers,
/Chris (also pretty fresh in Xen)
> Hello xen list.  I am an absolute novice with Xen, having never been
> able to set it up despite my several trials.  I have built a new, modern
> system (last computer was seven years ago) with the hardware
> virtualization technologies so I''m hoping to be able to run
Windows
> natively along side a graphical Linux desktop.
>
> Here is what I was imagining ...
>
> Dom0 = Gentoo
> DomU = Gentoo w/gui
> DomU = Ubuntu
> DomU = Windows XP
> DomU = Windows 2000
> DomU = Windows 98
> DomU = FreeBSD (multiple versions)
>
> My hardware is dual quad core Xeon processors with 8 GB of RAM and
> several hard drives in a RAID 6 array.
>
> 1) Is it better to have the "drives" that are exported to the
DomUs be
> partitions, files, LVM, etc.?
>
> 2) If somebody has a computer running Xen and a Microsoft and Linux OS,
> how does one switch control between them?
>
> 3) Does every component of the system need to be understood by the Dom0
> to be able to be utilized by a DomU?
>
> 4) If the Dom0 is x64, can a DomU be 32 bit?
>
> 5) If the answer to 4 is yes, then can that DomU then be migrated to a
> Xen computer with a Dom0 that is 32 bit?
>
> 6) Does the Dom0 need to statically partition the resources (RAM, CPU)
> to the DomUs, or is there a dynamic, kernel / Xen controlled allocation
> that is possible?
>
> Thanks for reading.  Let me know if I clarify anything.  I''ve
tried to
> be vague because I do not really know much at all about Xen.  I
don''t
> know what''s important to state or what is inconsequential 
I''ve read the
> official "Xen 3.0 Documentation" PDF from xen.org, but I have a
feeling
> that it is outdated, because I remember that being about the same as
> what I read years ago.
>
> -Charles
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>


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On Thu, Jan 15, 2009 at 9:32 PM, Charles Derringer
<charles@starvingfor.info
> wrote:
> Hello xen list.  I am an absolute novice with Xen, having never been able
> to set it up despite my several trials.  I have built a new, modern system
> (last computer was seven years ago) with the hardware virtualization
> technologies so I''m hoping to be able to run Windows natively
along side a
> graphical Linux desktop.
>
Consider the book "Running Xen" - http://runningxen.com

>
> Here is what I was imagining ...
>
> Dom0 = Gentoo
> DomU = Gentoo w/gui
> DomU = Ubuntu
> DomU = Windows XP
> DomU = Windows 2000
> DomU = Windows 98
> DomU = FreeBSD (multiple versions)
>
> My hardware is dual quad core Xeon processors with 8 GB of RAM and several
> hard drives in a RAID 6 array.
>
Seems reasonable given the hardware and RAM

>
> 1) Is it better to have the "drives" that are exported to the
DomUs be
> partitions, files, LVM, etc.?
>
This depends. There are some trade-offs. Performance vs. flexibility.

Image files giving the most flexibility, but with somewhat less performance.
Partitions/LVM/RAID more performance, but less flexibility.

You can mix and match based on your needs and there is a lot of questions
and analysis on the list about this
search xen.markmail.org for more info and/or asked more specific questions.

>
> 2) If somebody has a computer running Xen and a Microsoft and Linux OS, how
> does one switch control between them?
>
Think of the computers as being on a local network. VNC, Remote Desktop,
SSH, etc. all can work on the guests.


>
> 3) Does every component of the system need to be understood by the Dom0 to
> be able to be utilized by a DomU?
>
No, you can passthrough PCI devices directly to a domU. Doing this securely
requires an IOMMU (Intel VT-d) or
a very recent AMD IOMMU. IOMMU is a chipset feature, it and VT-d have also
been heavily discussed on this list.
There are some limitations without an IOMMU such as lack of support for a
HVM/Full virt (i.e. Windows) guest to get
a PCI device passed to it

>
> 4) If the Dom0 is x64, can a DomU be 32 bit?
>
Yes.

>
> 5) If the answer to 4 is yes, then can that DomU then be migrated to a Xen
> computer with a Dom0 that is 32 bit?
>
Probably. Haven''t tried it myself, but others can probably confirm.

>
> 6) Does the Dom0 need to statically partition the resources (RAM, CPU) to
> the DomUs, or is there a dynamic, kernel / Xen controlled allocation that
is
> possible?
>
The latest version of Xen support memory over commit, CPU over commit has
been available for a long time.


>
> Thanks for reading.  Let me know if I clarify anything.  I''ve
tried to be
> vague because I do not really know much at all about Xen.  I don''t
know
> what''s important to state or what is inconsequential 
I''ve read the official
> "Xen 3.0 Documentation" PDF from xen.org, but I have a feeling
that it is
> outdated, because I remember that being about the same as what I read years
> ago.
>
Xen is an open source project and sometimes the documentation is not the
greatest. There is quite a bit of effort going into this, but it will be
some time before it is considered good.

That being said, Xen is being used by a lot of people all over the world in
production, companies, universities, researchers, etc. There is a lot of
information on the
web (howtos, wiki information, etc. etc.) and quite a few books as well.

Hope that helps to get you started.

Cheers,
Todd

-- 
Todd Deshane
http://todddeshane.net
http://runningxen.com


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

christoffer@lindak.se wrote:
> I''ll try to address your last question about documentation: Yes it
is old,
> but someone is revising it as we speak. The pdf describes Xen 3.0.
> However, if you look at the html version instead, it''s on Xen 3.3.
In the
> appendix in particular, HVM is described, which is exactly what you need
> for your Windows domU:s.
> 
> Cheers,
> /Chris (also pretty fresh in Xen)
> 

Thanks Chris.  I''ll check out the newer, HTML documentation.

-Charles

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Todd Deshane wrote:

 >
 > Consider the book "Running Xen" - http://runningxen.com
 >


Thanks, I''ve bookmarked that site.


 >
 > This depends. There are some trade-offs. Performance vs. flexibility.
 >
 > Image files giving the most flexibility, but with somewhat less 
performance.
 > Partitions/LVM/RAID more performance, but less flexibility.
 >
 > You can mix and match based on your needs and there is a lot of
 > questions and analysis on the list about this
 > search xen.markmail.org <http://xen.markmail.org> for more info
and/or
 > asked more specific questions.
 >


Excellent.  Thank you.


 >
 > No, you can passthrough PCI devices directly to a domU. Doing this
 > securely requires an IOMMU (Intel VT-d) or
 > a very recent AMD IOMMU. IOMMU is a chipset feature, it and VT-d have
 > also been heavily discussed on this list.
 > There are some limitations without an IOMMU such as lack of support for
 > a HVM/Full virt (i.e. Windows) guest to get
 > a PCI device passed to it
 >


I''ll watch out for that in my reading.


 >
 > The latest version of Xen support memory over commit, CPU over commit
 > has been available for a long time.
 >


By "over commit" do you mean temporary bursting?


 >
 > Xen is an open source project and sometimes the documentation is not the
 > greatest. There is quite a bit of effort going into this, but it will be
 > some time before it is considered good.
 >
 > That being said, Xen is being used by a lot of people all over the world
 > in production, companies, universities, researchers, etc. There is a lot
 > of information on the
 > web (howtos, wiki information, etc. etc.) and quite a few books as well.
 >
 > Hope that helps to get you started.
 >
 > Cheers,
 > Todd
 >
 > --
 > Todd Deshane
 > http://todddeshane.net
 > http://runningxen.com


Thank you Todd.  I feel like I am prepared and pointed in the correct 
direction.

-Charles

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Sun, Jan 18, 2009 at 4:36 PM, Charles Derringer
<charles@starvingfor.info> wrote:
> By "over commit" do you mean temporary bursting?
>
Some details here:
http://blog.xen.org/index.php/2008/08/27/xen-33-feature-memory-overcommit/

Cheers,
Todd

-- 
Todd Deshane
http://todddeshane.net
http://runningxen.com

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Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users