[Ilugc] Virtualization
Bharathi Subramanian
ILUGC is planning to organize a one day Virtualization Workshop on Sun
Sept 14th. If you regularly use Virtualization tools on Linux Env and
willing share your knowledge by giving a demo.
Plz mail back to *me* with details about the Virtualization tool(s)
that you like to give demo (install, config and run).
Bye :)
--
Bharathi S
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Shrinivasan T
Welcome.
Eagerly waiting to hear from specialists.
Thanks for organizing.
--
dear,
T.Shrinivasan
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baskar k
On Tue, Aug 19, 2008 at 7:53 PM, Bharathi Subramanian
<sbha...@midascomm.com> wrote:
>
> Hi All,
>
> ILUGC is planning to organize a one day Virtualization Workshop on Sun
> Sept 14th. If you regularly use Virtualization tools on Linux Env and
> willing share your knowledge by giving a demo.
>
I'll try to demonstrate virtualization using Xen. Xen is a fairly
simple operating system that acts as a hypervisor that other OSes can
run on top of it.
Virtualization is a technique by which mutiple guest operating system
can be allowed to be run on a base operating system
related links
Home page - http://xen.org
Download - http://xen.org/download
Documentation - http://xen.org/xen/documentation.html
baskar.k
Kenneth Gonsalves
On 19-Aug-08, at 8:52 PM, Shrinivasan T wrote:
>> Bharathi S
>>
>> _______________________________________________
>> To unsubscribe, email ilugc-...@ae.iitm.ac.in with
>> "unsubscribe <password> <address>"
>> in the subject or body of the message.
>> http://www.ae.iitm.ac.in/mailman/listinfo/ilugc
>>
>
>
>
>
> Welcome.
>
> Eagerly waiting to hear from specialists.
>
> Thanks for organizing.
please avoid bottom posting
--
regards
kg
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benjamin
can be allowed to be run on a base operating system"
on "a base operating system" or "on the hardware"?
Kapil Hari Paranjape
On Wed, 20 Aug 2008, benjamin wrote:
> "Virtualization is a technique by which mutiple guest operating system
> can be allowed to be run on a base operating system"
>
> on "a base operating system" or "on the hardware"?
Usually, there _is_ a base operating system which is called the host.
The tasks of the host are (at least):
a. To make it convenient to create and manage guests.
b. To manage hardware access for the hosts.
Regards,
Kapil.
--
Arun Khan
> "Virtualization is a technique by which mutiple guest operating
> system can be allowed to be run on a base operating system"
>
> on "a base operating system" or "on the hardware"?
On a "base (or host) operating system".
VM has been there on mainframes for a long time (the Big Iron has a
layer of "base" OS to host multiple instances of guest OSs). Only in
the past few years, with advances in desktop CPU arch. and lower memory
cost, it has come to commodity PC hardware.
--
Arun Khan
Girish Venkatachalam
> I'll try to demonstrate virtualization using Xen. Xen is a fairly
> simple operating system that acts as a hypervisor that other OSes can
> run on top of it.
> Virtualization is a technique by which mutiple guest operating system
> can be allowed to be run on a base operating system
>
I will throw a few rupees worth information with whatever little I know
of virtualization.
Xen is a marvelous creation. And it beats VMWare hands down. I will say
why. I could have some outdated info here. VMWare might have caught up.
But at least this is what I know from what I learnt a year or so ago.
Typical case of OS running on bare metal (which is CPU, memory and
peripherals) is different from a virtualized environment in the sense
that the bare metal (hardware resources) is managed by a hypervisor.
The real OS has to make hypercalls to use the 'bare metal resources'
instead of accessing directly in the normal case.
Now the definition of an OS as taught in colleges is performed by the
hypervisor. So technically speaking we can call it an OS. At least a
slimmed down OS.
But the hypervisor is far from enough to do something useful. So we have
to have a real OS like NetBSD or GNU/Linux running as DOM0 over the Xen
hyervisor. So this is typically called the host OS. The DOMUs are known
as guest OSes. Many OSes have been ported to run on top of Xen.
x86 platforms come with four levels of protection for the purpose of
memory management. Ring 0, 1 , 2 and 3. Normally kernel runs in ring 0
with highest freedom and liberty. And userspace processes run at ring 3.
Whereas in the case of Xen, all four levels are used.
Now the main difference between Xen and VMWare is this:
" Xen does not emulate the underlying hardware completely. This
means that OSes have to be modified to run on top of Xen hypervisor. You
can never run an OS directly over Xen. Whereas VMWare does full hardware
virtualization which is a highly complex task. Thereby Xen achieves a
very high level of performance when compared to VMWare. But VMWare's
approach means that you don't have to modify the OS to run on top of
VMWare. "
So the design and code of VMWare and Xen are wildly different since the
goals though similar follow somewhat antipodal approaches.
There are other forms of emulators like Bochs and qemu which I regularly
use. This should not be confused with virtualization. qemu tries to
emulate the bare metal. But this happens at a very high level.
Thanks.
-Girish
rajasekhar kuppa
is this so in Xen 3.1 running on top of a Intel VT supported architecture?
I heard that running an OS with out changing it is now possible with the
above mentioned combination which is why CITRIX has bought Xen source .
I might have heard wrong but could some one shed some light on this please
!!
Raj
Rahul Sundaram
>
> Now the main difference between Xen and VMWare is this:
>
> " Xen does not emulate the underlying hardware completely. This
> means that OSes have to be modified to run on top of Xen hypervisor. You
> can never run an OS directly over Xen. Whereas VMWare does full hardware
> virtualization which is a highly complex task. Thereby Xen achieves a
> very high level of performance when compared to VMWare. But VMWare's
> approach means that you don't have to modify the OS to run on top of
> VMWare. "
>
> So the design and code of VMWare and Xen are wildly different since the
> goals though similar follow somewhat antipodal approaches.
Not really. VMWare has a hypervisor based solution for quite sometime now.
http://www.vmware.com/products/vi/esx/
If you compare the model of VMWare ESX and Xen, they are quite similar
where they both have mini operating systems running as hypervisors. What
is different is the KVM one where Linux itself as a "hypervisor"
http://udrepper.livejournal.com/15795.html
http://blog.codemonkey.ws/2008/05/truth-about-kvm-and-xen.html
Rahul
benjamin
> Usually, there _is_ a base operating system which is called the host.
>
> The tasks of the host are (at least):
> a. To make it convenient to create and manage guests.
> b. To manage hardware access for the hosts.
>
in Xen, would you call Dom0 the host?
Dom0, a special domain (VM) too runs on top of Xen
ESX, COS is not the host as VMkernel runs the hardware
Here too, COS is a special VM running on top of VMkernel.
There is also something similar in Hyper-V
In Hypervisor based Virtualisation Softwares, I do think the control consoles
are host as they do not really host the VMs. They can just communicate with
the Virtualization Layer which other user created VMs cannot. And Hypervirsor
based virtualizations softwares are installed on bare metal.
Of course, VirtualBox, VMware server, VPC all needs bases OS as the host.
Yes, the tasks you mentioned are right.
benjamin rualthanzauva
Kapil Hari Paranjape
> in Xen, would you call Dom0 the host?
You are right about the fact that even Dom0 is "only"
a special domain.
My statement was made from a usage perspective rather than
as strict logical dependency.
Regards,
Kapil.
--
Raja Subramanian
<sund...@fedoraproject.org> wrote:
> Girish Venkatachalam wrote:
>> So the design and code of VMWare and Xen are wildly different since the
>> goals though similar follow somewhat antipodal approaches.
>
> Not really. VMWare has a hypervisor based solution for quite sometime now.
>
> http://www.vmware.com/products/vi/esx/
>
To make things even more identical, VMWare also supports paravirtualization:
http://www.vmware.com/interfaces/techpreview.html
http://www.vmware.com/interfaces/paravirtualization.html
- Raja