If you would like to read the next part in this article series please go to Upgrading to Hyper-V 2008 R2 (Part 2).
Introduction
Microsoft’s Hyper-V was nice as first generation products go, but Hyper-V 2008 R2 is far superior to the original release. A new feature called Live Migration allows you to move virtual servers from one host to another with no down time. In addition, Microsoft has made some tremendous improvements to Hyper-V’s performance and scalability. For example, the original Hyper-V release supported 16 virtual processors, but Hyper-V 2008 R2 supports 32!
If you are already using Hyper-V, you probably can not wait to take advantage of these, and all of the other new features. In order to do that though, you will have to upgrade your existing host servers. In this article series, I will explain what your options are for upgrading from Hyper-V to Hyper-V 2008 R2.
Before I Begin
Before I get started, I need to clarify some of the terminology that I will be using throughout this article series. There are two different flavors of Hyper-V 2008 R2. One of these flavors installs on top of Windows Server 2008 R2 as a server role. The other flavor is a standalone server. For the purpose of this article series, I will be referring to the Hyper-V server role as the Hyper-V R2 Role. I will be referring to the standalone version as Hyper-V R2.
Just as there are two versions of Hyper-V 2008 R2, there are also two versions of the original Hyper-V. I will be referring to the standalone version as Hyper-V Server and I will refer to the server role as the Hyper-V Role.
Upgrading from the Hyper-V Role to the Hyper-V R2 Role
Microsoft gives you three different methods for upgrading from the Hyper-V role to the Hyper-V R2 role. You can perform an in place upgrade, an export / import, or a backup and restore. I will discuss each of these options in detail.
Performing an In-Place Upgrade
As the name implies, an in-place upgrade involves installing Windows Server 2008 R2 over top of your existing copy of Windows Server 2008, which will cause Hyper-V to be upgraded in the process. On the surface, performing an in-place upgrade sounds really simple. There is more to it than meets the eye though.
The first thing that you need to know about an in-place upgrade is that a compatibility report displayed during the upgrade process tells you that you need to uninstall the Hyper-V role before you continue. According to Microsoft Knowledgebase article number 957256 this is an erroneous error message that can be disregarded.
A much more pressing consideration is that the Hyper-V R2 role does not support saved states that were created while the server was running the Hyper-V role. This can be a major issue even if you do not use saved states, because snapshots use saved states. The Hyper-V R2 role does not have any trouble dealing with offline snapshots (snapshots taken while a virtual machine is shut down), but it does have some compatibility issues with online snapshots (snapshots made while the virtual machine was running).
The easiest way to perform an in-place upgrade is to perform a full backup of your host server, delete your snapshots, and then shut down your virtual machines and perform the upgrade. Of course getting rid of your snapshots is not always practical. The upgrade process will involve less work if you can manage to delete your snapshots, but there is a workaround if getting rid of your snapshots is not an option. Incidentally, shutting down the virtual machines is a requirement of the upgrade process.
Rather than trying to explain the workaround right now, I am going to walk you through an upgrade later in this series, and when I do, I will show you the workaround for dealing with your snapshots.
Before I move on, there is one more thing that I need to mention. The integration services have changed in the Hyper-V R2 role. Therefore, after the upgrade process completes you will have to manually update the integration services on each virtual machine.
It is worth noting that if you have virtual machines that are running Windows Server 2008 R2, then the Programs and Features list will give you the illusion that the integration services have not been installed. To find out if the integration services have been installed or not, check the list of installed programs for an update named KB955484. This is the new name for the Integration Services.
Exporting and Importing Virtual Machines
The second method for upgrading the Hyper-V role involves exporting your your virtual machines, and then importing them into the Hyper-V R2 role. The same basic limitations apply to this technique as apply to an in place upgrade.
Although the Hyper-V role will allow you to export a virtual server that is currently in a saved state, you will be unable to start the virtual machine within the Hyper-V R2 role until you get rid of the saved state.
The limitation to virtual machine snapshots also applies to exporting and importing virtual machines. If you can get away with it, it is best to delete all of your virtual machine snap shots prior to shutting down and exporting your virtual machines. If that is not an option, then you can use the same workaround that I mentioned in the previous section.
As was the case with an in-place upgrade, you must update the integration services for each virtual machine that you import into the Hyper-V R2 role.
Although the export / import method is fairly painless, using this method can result in a considerable amount of down time. My experience has been that the export process can take several hours for some virtual machines. The actual amount of time that the export process takes depends on the size of the virtual machines that you are exporting and on your hardware capabilities.
Backup and Restore
The third method that Microsoft recommends for upgrading to the Hyper-V R2 role is to use a Hyper-V aware backup application to backup your virtual machines. Once the backup has completed, you can install Windows Server 2008 R2 and the Hyper-V R2 role, and restore your backup.
The interesting thing about this method is that Microsoft does not seem to make any mention of issues related to saved states or virtual machine snapshots. The only caveat that Microsoft lists for this particular method is that once you have restored your virtual machines, you will have to install the latest version of the Integration Services. I have to admit that I have not tried this upgrade method yet, but I hope to get a chance to try it before this article series is complete so that I can report my findings.
Conclusion
So far I have explained the basics of upgrading from the Hyper-V role to the Hyper-V R2 role. In Part 2, I will continue the discussion by walking you through a Hyper-V upgrade. Later in the series, I will discuss some other types of Hyper-V upgrades that you can perform.
If you would like to read the next part in this article series please go to Upgrading to Hyper-V 2008 R2 (Part 2).
