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P2V Tip: VMDK Pre-Build

I am always looking for ways to make a physical-to-virtual conversion go better. While I love the venerable VMware vCenter Converter for most workloads, I still find situations where I can't allocate the time to do a conversion this way.

In addressing some unstructured data systems, a new approach revealed itself: the VMDK pre-build. When I say unstructured data, I am simply referring to situations such as a very large number of very small files. While I'd rather deal with a database putting this content into a blob format, I'm often dealt the unstructured data card.

So, what do I mean by a VMDK pre-build? Basically, I deploy a generic virtual machine within vSphere and attach an additional VMDK disk. From that generic virtual machine, I launch a series of pre-load operations onto the additional VMDK disk. The pre-load copies the unstructured data ahead of time to a VMDK disk. This can be done via a number of tools, including the quick and easy
Robocopy scripting options, RichCopy graphical interface and more advanced tools that you can buy from companies like Acronis or DoubleTake. By using one of these tools to pre-populate the VMDK file, you can save a bunch of time on the actual conversion.

Taking the VMDK pre-build route, of course, assumes that the Windows Server has a C:\ drive that is separate of the collection of unstructured data. At the time of the conversion, using VMware vCenter Converter for the C:\ drive will take a very short amount of time. After the conversion, you simply remove the VMDK from the generic virtual machine, and attach it to the newly converted virtual machine. There, you've saved a bunch of time.

The tools above can be tweaked to add some critical options on the pre-load of the VMDK disk. This can include copying over Windows NTFS permissions, as well as re-running the task to catch any newly added data. Robocopy, for example, will proceed much quicker once the first pass is completed and pick up only the newly added data.

The tip I provide here isn't the solution for a SQL Server or Exchange Server, of course, but the use cases can apply to anything that has a large amount of data that may take a long time to convert via the traditional methods.

Have you ever used this trick in performing your P2V conversions? If so, share your experience here.

Posted by Rick Vanover on 05/25/2010 at 12:47 PM


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