WindowsNetworking.com Monthly Newsletter of February 2010 Sponsored by: Syncplicity
Welcome to the WindowsNetworking.com newsletter by Debra Littlejohn Shinder, MVP. Each month we will bring you interesting and helpful information on the world of Windows Networking. We want to know what all *you* are interested in hearing about. Please send your suggestions for future newsletter content to: email@example.com
Windows Server 2008 R2 includes Hyper-V R2. The R2 iteration of Hyper-V adds several new features and functionalities to the virtualization platform, and one of the best is Live Migration, which is supported in the Enterprise and Datacenter editions. Sure, Server 2008 already had something called Quick Migration, which made it possible to migrate virtual machines with only a few seconds of downtime. But for many administrators - especially those comparing Hyper-V to VMware - "quick" wasn't quick enough.
The problem is that VMware's VMotion technology promises no downtime whatsoever; you can migrate a virtual environment from one physical machine to another seamlessly, with no impact on the users who are using those virtualized servers. That set the bar high, and made Quick Migration look like an also-ran. In order to remain competitive, Microsoft almost instantly had to remedy the situation, and they did. Live Migration, like VMotion, lets you move virtual machines from one physical server to another with no perceived downtime at all.
The catch - for both VMotion and Live Migration - is that this seamless migration process requires the data to be stored in a shared arrangement such as a SAN array. In the original Windows Server 2008, cluster nodes were not able to communicate with shared storage. What makes it possible for R2 to do this is another new feature called cluster shared volumes. So, to use Live Migration, you have to add and configure failover clustering. Then you can migrate a virtual machine (while it's running) from one cluster node to another. The VMs are stored on the SAN.
What else do you need to take advantage of Live Migration? Well, first of all, all of the cluster nodes have to be running Windows Server 2008 R2 or the standalone Hyper-V Server 2008 R2. There are a couple of "little things" that could trip you up if you are not aware of them: The NTLM authentication protocol has to be enabled on all the nodes, and the drive letter for the system disk also has to be the same on all of the nodes.
Each machine needs to have a dedicated NIC configured for the virtual network to carry Live Migration traffic (this is separate from the networks for storage, for the VM, and for communication between the cluster nodes). You can use a VLAN if you do not have enough network adapters.
Another "gotcha" is that the storage system on the failover cluster needs to be identical. When migrating VMs on previous versions of Hyper-V, the machines had to have identical processors. Thanks to Processor Compatibility Mode (PCM), this is no longer the case - as long as the processors are built on the same architecture (that is, within the same vendor processor family). However, PCM does not allow migration between AMD and Intel processor-based machines. Intel's Virtualization Technology (VT) also includes a feature called FlexMigration, which works with PCM to make servers expose the same instruction set to applications even if they are based on different processor generations (it also works with VMware VMotion). You can find out more about FlexMigration here.
For detailed information on how to set up Hyper-V with failover clustering, see this TechNet article.
So, is all that worth the trouble? Many IT pros think so; in fact, many were unable to take Hyper-V seriously as an alternative to VMware until Live Migration became available. This ability becomes very important when practicing "preventative medicine" because it lets you migrate your mission critical VMs to another machine as soon as you see signs that the machine on which it's running on may fail, rather than waiting until disruption of operations occurs. You can also move your running VMs to another machine for better performance, scaling or consolidation. This gives you a lot more agility in the server room or datacenter, and you can keep VMs online even while performing hardware maintenance, applying security updates, etc. That is certainly good news for admins because it means you can do these tasks during normal business hours instead of waiting to do them after hours so users would not be affected.
What do you think of Live Migration in Hyper-V R2? Is it all it is cracked up to be? Will it finally make Hyper-V a VMware killer? Or is it too little, too late? You can write to me at firstname.lastname@example.org with your comments and questions.
By Debra Littlejohn Shinder, MVP
Quote of the Month - "Im a great believer in luck, and I find the harder I work, the more I have of it." - Thomas Jefferson (1743 - 1826)
3. WindowsNetworking.com Articles of Interest
What Is Offline Domain Join?
Windows 7 or Windows Server 2008 R2 computers can use the new feature called "Offline Domain Join". This process requires the Windows 7 or Windows Server 2008 R2. The procedure requires two steps:
First the computer account is created or provisioned on the domain controller and the resulting information is stored in the metadata. This information is then transferred to the joining computer. The workstation then performs the joining part without having the connectivity with the domain controller.
You need to use Djoin.exe on the domain controller to accomplish above. You can use Djoin.exe /? to see the syntaxes.
An example is given below:
Djoin.exe /provision /domain Name_Of_the_Domain_To_Be_Joined /machine Client_Computer_Name /savefileFile_Name.txt
A new remote access technology known as DirectAccess is included with the combination of Windows 7 and Windows Server 2008 R2. A number of Windows platform technologies are brought together to make DirectAccess work. The network protocol that drives DirectAccess is IPv6 and the DirectAccess server must be IPv6 capable. For that reason, you need to have IPv6 enabled on all interfaces on the DirectAccess server. I have heard of some cases where people have turned off IPv6 on their DirectAccess servers, and it caused DirectAccess to stop working. This problem can be a very one difficult to troubleshoot, since who would think that someone would have disabled IPv6 on a server that is designed to run a very IPv6 centric technology?
I have heard a lot about Server Core and I like the minimalist idea. Here is my question and it's a pretty simple one: Can I run Exchange on Server Core, or does it require a full installation of Windows Server 2008? If not, why not? Thanks! - Len K.
Well, the answer is no - and yes. Server Core is a command line implementation of Windows Server 2008 or 2008 R2 that is designed to run one of the five "core" server roles: file server, DHCP Server, DNS Server, Media Services Server or Active Directory. It can also run the IIS and Hyper-V roles. It is not designed as an application platform. That said, Server Core can run certain management tools and utilities and it does include a few GUI tools such as Task Manager.
Running Exchange or other such applications on Server Core is not supported by Microsoft. However, apparently some folks have been able to get it installed and running, as shown here.
Bottom line: If you just like to experiment, you might be able to get Exchange running on Server Core, but its not something you would want to do in a production environment, especially with an application thats as important as your email server.