The speed of creating a Fixed Sized VHD

You might want to read this article on how to different ways to create a fixed sized VHD take very different amount of time.

Creating a 500GB fixed sized VHD on the EVA storage took only 49 minutes or almost 10 times faster.

Creating a 500GB fixed sized VHD on the Direct Attached Storage (DAS) on the recovery Hyper-V Server where the DR instance of the Exchange 2010 VM lived took a little over 8 hours.

Of course this is not a problem but very costly if the customer has to pay by the hour.

I was happy to have started the fixed disk creation the evening before so when I looked this morning both VM’s were ready and waiting to be used.


The fast FC disk image creation


And the slow SATA image creation


Creating a fixed sized VHD takes a fair amount of time because we zero-out all the disk space that has been requested. The advantage is that if the disk has enough free space (see previous defrag blog) the entire fixed size VHD can be written contiguously which improves speed and efficiency. Take a look at Ben Armstrong’s blog for more background.

If you are the impatient type of administrator and you don’t care a great deal about security you might want to look at VHD Tool v2 which was created by Ben Armstrong and released in January 2011 which not only created huge fixed sized VHD’s extremely quickly but also has a repair option.


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