My Notes to Myself and Others... : Hyper-V

Hyper-V security guide

Erik Rozman — Sat, 04 Apr 2009 16:20:31 GMT

This Solution Accelerator provides instructions and recommendations to help strengthen the security of computers running the Hyper-V role on Windows Server® 2008. It covers three core topics: hardening Hyper-V, delegating virtual machine management, and protecting virtual machines.

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Hyper-V or VHD Backup

Erik Rozman — Sat, 27 Dec 2008 14:36:44 GMT

One of the main advantages in virtualization is having the ability to quickly recover
failed systems. By turning a system into a virtual system you are actually turning
it into a file that can be used on any system that has Hyper-V installed on it thus
enabling quick recovery of a failed system.

The main problem is that to be able to backup a VHD file you need to stop the
virtual machine. Now obviously, on mission critical systems you can’t stop a system
every time you want to back it up. To overcome this issues, you can us the Volume
Shadow Service (VSS) mechanism to take a snapshot of the volume that stores
the VHD files and then copy the relevant files to external storage.

Taking a snapshot of a VHD file is possible since Windows 2008 has a built-in Hyper-V
VSS Writer that brings the virtual machine’s hard drive (the VHD file) to a consistent
state.

Once the snapshot is taken, you can manually mount the snapshot and back it up.

To do this, you should use a tool included with Windows 2008 called ‘diskshadow.exe’.
Diskshadow is an interactive interface to VSS. It has a vast list of commands but if we
concentrate on our specific issue you need to issue the following commands:

set context persistent
[You can set it to volatile if you would like to have the snapshot deleted once you exit
the diskshadow.exe application]

add volume <driveletter> alias <alias_you_choose>
(for example add volume t: alias VHDBackup)

set verbose on

create

Once you complete this set of command you have a snapshot stored.You can view
the stored snapshots by executing the following command:

list shadows all

Once you are ready to back the VHD up, expose the snapshot you would like to use by
using the following command:

expose <ShadowID> <Drive:>

Now you can access the data as you would any drive on your system. To hide the snapshot
execute the following command:

unexpose t:

The major advantage of this feature is that you don’t need to stop a virtual machine
to back it up. From my experience the process of taking a snapshot is relatively quick
and it does not tax a system but I would advise that you do it during afterhours.
One more point to consider is disk space,monitor it closely and delete unused snapshots.

Hyper-V Top Issues

Erik Rozman — Fri, 26 Dec 2008 09:41:52 GMT

Lately, we have been messing around with Hyper-V (by saying we,I actually mean
mean myself and the person that won’t tell me his Kazakh name…).

The technology itself is very cool, but as always it has it’s quirks. Oddly enough,
after we ironed out most of the issues a blog post appeared on the ‘Ask the Core
Team’ blog describing the top issues that they have encountered.

The post is very useful (and would have been really great a couple of month ago… :)).

Click here for the post.

Hyper-V experiences: Physical to Virtual

Erik Rozman — Mon, 20 Oct 2008 16:02:07 GMT

Hyper-V is cool. It’s simple to install and manage yet it has quite a few interesting quirks
that need to be worked out, an example of such a quirk is installing it on HP servers that
have teaming enabled:

http://support.microsoft.com/kb/950792

An additional interesting point that is worth mentioning is that if you would like to manage
a Hyper-V server, and access the consoles of the guest operating systems, you should
do so by installing RSAT on your desktop or by working at the console of the Hyper-V
server itself. If you try connecting by using RDP, you will not be able to use your mouse
inside the guest OS.

A few weeks ago, I completed the migration of an old physical server to a virtual environment
(Hyper-V based on Windows 2008). The following is a distilled version of my experiences:

Before starting, I decided to test the process. I made the mistake of not using the exact same
hardware that the original system was built upon. Basically I installed Windows 2003, installed
a few applications, mapped a drive and shut down the test system. I took an image of the
test system, built a virtual machine and applied the image to it.

I took a snapshot after applying the image (if something goes wrong) and started the test
virtual machine. The system started without any major issues:

The system had to be re-activated.
Missing drivers.
And (obviously), integration services had to be installed to enable access to the network.

Happy with the results, I was ready to proceed with the live system. I went through the same
process, yet when I started the virtual machine a blue screen welcomed me and the system
simply looped(restart,bluescreen a.k.a. happy happy joy joy).

At this stage, I started kicking myself for not using the exact same hardware for the test but
it was too late. Luckily I requested a large enough change window so having the production
system wasn’t a problem(yet).

There is a very useful post (actually step-by-step) for doing such a migration and avoiding
the blue screen but in my case it simply didn’t help…

After several unsuccessful attempts to manually fix the issue, I decided to reinstall the OS
over the current installation. I used a pre-SP2 CD to install the OS (later on this turned out
to be a mistake). The installation took quite some time yet when it was finished I was able to
boot into the guest OS with several problems:

Activation-Since I had no networking I ended up calling the activation hotline (loved
the voice activated system).
Installing integration services- since I used a pre-SP OS to reinstall, Hyper-V would
not install the integration services. I downloaded SP2, added it to a mounted
hard drive and installed it…once done the integration services were installed.
[Take a look at a similar yet different post on this issue.]

In summary, the process was relatively simple yet you have to know what to expect. I haven’t
tried it, yet I am sure that with Windows 2008 and Vista the process is simpler since they are
hardware independent yet my advice to you(specifically if you are looking at production systems):
test before you proceed!

Hyper-V and HP Servers

Erik Rozman — Fri, 26 Sep 2008 07:09:35 GMT

…Or why is my server stuck at 53% of an update.

This one is a real pearl. I was installing Hyper-v on a relatively standard
DL360 G5, after installing the role I installed Hyper-V RTM Update (KB950050)
and I was asked to restart the system to complete the update.

Sounds simple enough,right? Well after the restart I was waiting for the 3rd stage
of the update to complete…so the system is counting percents and it stops counting
at 53%. After waiting for about half an hour, I decided to cold boot it yielding the
same result.

A bit frustrated (to say the least) I started searching the Internet,and guess what:
this is a known issue:
http://support.microsoft.com/kb/950792

Basically what the KB says is that Hyper-V doesn’t play nice with the HP teaming feature
(which no one uses…I am cynical Mr. Wolf) and you have to rename the DLL it uses
so it won’t start when you update Hyper-V…

I found this whole situation odd:First of all why does this happen, and why does the KB
say 54% when it actually seems to be 53% (based on my search of the Net).

Hyper-V is in the wild

Erik Rozman — Fri, 27 Jun 2008 08:01:47 GMT

Yesterday,and ahead of time, the final version of Hyper-V was released. You
can find product details at the following link. If you would like to download the
update for your Windows 2008 system, click here.

www.microsoft.com on Hyper-V

Erik Rozman — Thu, 26 Jun 2008 19:46:27 GMT

There is nothing better then dogfooding to prove that you believe in your
product. I stumbled upon a post on the Windows Server Division Blog
describing the process of moving the microsoft.com website to Hyper-V:

http://blogs.technet.com/windowsserver/archive/2008/06/25/microsoft-com-powered-by-hyper-v.aspx