With the increasing popularity of virtualization, you may be faced with the task of moving your physical servers to virtual server guest images. There are several physical to virtual (P2V) products available that can help with the conversion process, including:
- Microsoft’s free Virtual Server Migration Toolkit available at http://www.microsoft.com/windowsserversystem/virtualserver/evaluation/vsmt.mspx
- VMware’s free Converter 3.0 Beta available at http://www.vmware.com/products/beta/converter/.
- Platespin’s PowerConvert available at http://www.platespin.com/products/PowerConvertMain.aspx
The first two products are available as free downloads and PowerConvert is $280 per conversion. The Virtual Server Migration Toolkit requires a Windows Server 2003 server (Windows XP x64 for non-production) and supports the Virtual Server 2005 Virtual Hard Disk (VHD) format to create guest images for Virtual Server 2005. VMware’s Converter 3.0 is still in beta, although I’ve had good success using it to create P2V VMware Server images. Although Converter gives you the option of changing the partition size of a hard disk during the conversion process, I suggest you avoid this feature because it can potentially cause the conversion to fail. I’ve also had better results when running Converter on a separate server than the server I was converting, although Converter does allow you to run a local conversion. PowerConvert can't be installed on the machine that's being converted, and the image conversion server must be installed on a Windows 2003 or Windows 2000 server. PowerConvert’s licensing is unforgiving, and you might burn a license on an unsuccessful conversion, requiring a call to Platespin to obtain an additional license for the failed conversion. All these products work reasonably well and will save you time during the migration process from the physical to virtual world--or will they?
This brings up the old question of whether to upgrade or wipe and reinstall a clean copy of the OS and programs on a server--but with a twist. The main issue here is the converted image will be only as stable as the server it was built from. If your physical server has corrupted OS files or programs the corruption will be carried into the virtual world. These conversion utilities do a pretty good job of recognizing hardware-specific drivers, but I suggest removing any hardware-specific programs like hardware-monitoring programs prior to the conversion. If a server has been in service for awhile, there’s a good chance that at least one or more files on the server are damaged, corrupted, infected with a virus or spyware, or has some other issue. When possible, I suggest rebuilding a fresh virtual machine (VM), installing the necessary programs, and moving only the data over from the physical to the virtual server guest. If you’ve pre-staged base OS virtual server images, you should have a head start on building a new virtual server. Although this is more work up front, you'll probably encounter fewer problems over the long run. If you develop problems with the converted machine, it may be very difficult to determine if these problems arose from the conversion process or you simply had some problems with the physical machine prior to the conversion. It may appear that the converted server is working fine, only to discover that the server crashes when installing the next program, patch, or service pack. When trying to troubleshoot these problems, you'll probably receive very obscure error messages that may have nothing to do with the “real” problem. Don’t expect an error message from the server similar to “I’m having problems running because my OS was corrupted prior to the P2V conversion process.”
That being said, there are still some other scenarios in which P2V makes sense, such as server versioning or creating disaster recovery images for quick recovery of physical servers. If you plan to use a P2V tool, here are some basic suggestions:
- Clean up the physical server. Make sure it has the latest patches and service packs. Review the Event Log and resolve any error messages. The converted server is only as good as the source server.
- Remove hardware-specific programs such as monitoring software.
- Designate a fast server with a lot of RAM, space, and fast hard drives to be your dedicated conversion server. Although some P2V programs let you install the program directly on the machine that will be converted, I’ve had better results running the conversion process on a separate server. The conversion process is very intensive and can take from a few to more than 24 hours to perform the conversion depending on the amount of data that must be converted. When possible, use a Gigabit connection to the physical server you want to convert. Because of the load it places on the server, it’s best to run these conversions after hours.
- Don’t repartition the drives during the conversion process; it might cause the conversion process to fail. For each P2V conversion, you'll have a significant amount of time invested in the conversion process. The last thing you want is an error message that the conversion failed at the end of a very long conversion process.
Although these P2V conversion utilities are useful, I suggest going the conservative route and rebuilding the server from scratch on the virtual server platform whenever possible.
If you plan to consolidate a number of servers on a single host, are using locally attached storage or NAS, need the highest virtual server performance, and have a host server that is listed on VMware ESX’s Server compatibility list, consider using the ESX Starter Kit. Although it doesn’t support a SAN and the other Enterprise Features of VMware Infrastructure Enterprise, it will give you better performance and has less overhead than running Windows 2003 or even Linux as the host OS to run your virtual server guests.