How Good is Hyper-V based Virtual Servers?

It has been over two years since the initial release of Hyper-V. Many minor enhancements have been made to Hyper-V while the core remained the same. The initial Marketing push of Hyper-V seem to have slowed down on Microsoft's part, now that Windows Server 2008 is fairly old and most people in the industry would be familiar with Hyper-V.

I wonder what type of systems are being used on Hyper-V based Virtual Servers. Is it still primarily for test, development and prototyping?

While some large scale applications like SQL Server may not be most suitable for Virtual Server Instances, it is perfectly possible for Hyper-V based Virtual Machines to carry out production level work.

We know it because we have had a Virtual Server Instance hosting over 275 Websites!

As far as CPU and Memory utilzation goes, Hyper-V Machines are almost as good as a real server. The memory is dedicated to the server, and CPU is real. However, as the number of guest instances grow, it can put a strain on the storage sub system. The overall performance of the guest machines will be limited by the performance of the storage system.

If the storage system can keep up with the demands of all guest machines, all Hyper-V based Virtual Servers will perform like stand alone servers.

We have run performace tests on both the Hyper-V Host and Guest Machines to verify this. There is negligible difference between the physical and virtual server.

If you are considering deployment of production Sites on a Hyper-V based Virtual Server, it is perfectly viable.

Ubuntu 8.10 on Hyper-V

Reporting successful installation of Ubuntu 8.10 Server Edition (With LAMP) on Hyper-V. No patch was necessary like it was for Ubuntu 7.10. Over a Remote Desktop connection to the Hyper-V host, installation screens appear very slow. But the installation was otherwise smooth.

Remember to use a 'Legacy Network Adapter' for the virtual machine if you would like networking to work out of the box. Installing Linux Integration Components should enable standard Network Adapter and improve network performance.

I have yet to try Linux Integration Components on an Ubuntu Installation.

If you know a tutorial for installing the Integration Components, please post a link.

Ubuntu Patch for Hyper-V

My original post about installing Ubuntu 7.10 on Hyper-V had a link to a patch that you needed to apply before installing Ubuntu 7.10 on Hyper-V. The original link to the patch seems no longer pointing to the right thread on the Citrix Forum. I received some requests for an update on this patch, and since I had a copy, I am leaving it here for download.

If you have any Ubuntu 7.10 ISO in the same folder where this patch is being run, it will fix those ISO and you should be able to install Ubuntu on Hyper-V without any issue. How stable is Ubuntu on Hyper-V? Well we do have Ubuntu Servers on Hyper-V running production Web Sites and so far they are working great. No linux Integration Components installed yet.

I take no credit for this patch, and I wish I knew who originally posted it on the citrix forum.

Download the patch (491KB)

Hyper-V SCSI vs IDE Boot

Looking at the number of searches relating to this issue, it appears to be the biggest concern about Hyper-V so far.

While it is not acceptable that a Virtual Machine must boot from an IDE drive interface when the underlying storage is SCSI, it is possible that the IDE performance in Hyper-V could be better than pre-existing virtual SCSI storages (Virtual Server, for example). The virtualization team on Microsoft explains it better, but the new synthetic drivers on Hyper-V utilizes a much better way of providing virtualization, resulting in better performance. It is possible that the IDE driver in Hyper-V can perform better than SCSI driver in Virtual Server 2005.

We have yet to run a performance comparison between Hyper-V IDE and Virtual Server 2005 SCSI. However, once the integration services (synthetic drivers) installed on a Windows 2003 guest machine, it appears pretty fast.

Also, a SCSI hard drive can be added to a Virtual Machine and used as the data storage. We often seperate boot and data drives on servers anyways. Having a seperate data drive makes it easy to backup virtual machine data.

These of course, are just work arounds until Microsoft figures a way to boot Hyper-V machines from SCSI.

They must be working hard on it. 

Hopefully soon we will be able to run some performance comparison between Hyper-V and Virtual Server guest machines.

Networking issue with Hyper-V External Virtual Network

Pretty much like Virtual Server 2005, Hyper-V has options to create virtual network cards for guest machines that directly maps with a physical network adapter on the host machine. There is  an important issue that may surprise you, however, especially if you are working on a remote server.

When you create a virtual network and map it to a physical Network Adapter (External Virtual Network), Hyper-V automatically removes all protocols from the physical Network Adapter on the host machine and enables Virtual Network Switch Protocol. This means TCP/IP protocol is also removed! The host server will appear disconnected/offline from the outsite world. If you were working over remote desktop, you will be kicked out, and won't be able to connect anymore.

All you have to do is re-enable TCP/IP on the physical Network Adapter in order to bring the server back online. Which of course you can't do unless you are logging in locally.

It is not a big deal if you have a second network card that is also connected to the Internet. In fact thats how I was saved, twice.

Why does Hyper-V remove all protocols from the physical network adapter except virtual networking? Is there some stability issues? Security issues? poor performance? I have yet to check the documentation on this.

But if you are reading this before it is too late, at least you can be prepared.