Sunday, December 14, 2008

Transitioning to HyperV

For the last few years, I have used Virtual Server 2005 to host virtual machines for testing different Dynamics GP environments, and for hosting different development environments. Some clients still use SQL 2000 and GP 8, while others are using SQL 2008 with the latest GP 10 service pack. Maintaining those configurations on a single physical machine typically isn't practical, so Virtual Server offered a great way to easily maintain and backup multiple server configurations. Virtual Server uses the same VHD files as Virtual PC, but I found that it was more convenient to use, easier to manage VMs, and seemed to be faster than Virtual PC.

I've finally built a new Windows 2008 Server, so I'm going to be transitioning my virtual machines over to HyperV, which is the replacement for Virtual Server 2005. Because of the memory requirements of virtual machines, I've installed the 64-bit (x64) version of Server 2008, which allows me to get past the 3GB / 4GB limit of 32-bit windows. The desktop machine I used for Server 2008 only supports up to 8GB of RAM, but I figure that should allow me to pretty comfortably host up to 4 virtual servers (typically using 1.5GB of memory each)--more than I need running at any one time.

I'm still learning about HyperV and how it is different from Virtual Server 2005, and in which ways it is the same, so for the time being I'll offer some links to articles that found helpful.

My focus is not just learning and understanding the HyperV features, but also understanding how to perform equivalent maintenance operations and processes in HyperV to replace the tricks I learned with Virtual Server 2005. For instance, what is the best way to backup a HyperV image? The files that are created by HyperV are slightly different than VS 2005, so I need to learn what to backup, when, and how (i.e. Can I write a script to pause the VM and run a backup like I did with VS 2005?). Also, can I migrate an existing VS 2005 VHD file to HyperV (the answer is yes), and if so, what steps do I need to complete to get all of the server features working properly in HyperV? (still working on this one...)

To get started, here are a few articles on HyperV by Janique Carbone on the web site that do a great job of explaining the basics of HyperV and some of the new HyperV features.

HyperV Integration Services: My interpretation is that this is effectively the replacement / upgrade for the old "Virtual Machine Additions" in Virtual Server and Virtual PC. You will definitely want to install these in your VMs (it makes the mouse 'usable', just like VM Additions).

Understanding and Using HyperV Snapshots: I still have alot of questions about HyperV snapshots, but so far, it seems like an amazing feature that works great.

And here is a nice video she created showing how simple it is to create and use snapshots:

What is pretty wild to me is how HyperV maintains 'branches' of snapshots, so it seems you can revert to a prior snapshot, then create new snapshots to create a new 'branch'. This is a pretty powerful feature, especially considering it only takes seconds to create or apply a snapshot.

But the caveat is that it can produce alot of permutations of your virtual server, so you'll have to learn how to manage those snapshots effectively so that they can be used in a meaningful fashion and not pile up over time to the point where they make a mess.

One small recommendation I have so far for taking snapshots is to try and log out of all sessions on the server before taking a snapshot. If you don't logout, your remote desktop connections will be saved as a disconnected sessions that you'll end up having to clear if you ever revert.

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