Owner's manual

The size of a dynamically expanding VHD is as large as the data that is wrien to it. As more data is wrien to a dynamically
expanding VHD, the le increases to a maximum size. A dierencing VHD is similar to a dynamically expanding VHD, but it contains
only the modied disk blocks of the associated parent VHD. Dynamically expanding VHDs are useful for tesng environments
because there is less impact if you have to rebuild the VHD. For example, some of the tests performed for this report used mulple
dynamically expanding VHDs, each with a dierent Windows image. Fixed VHDs are recommended for producon.
New Hyper-V Performance
VHDX
A new Hyper-V VHD format introduced with Windows Server 2012 that
increases storage capacity from 2TB to 64TB.
25 Percent More Throughput with Windows Server 2012 Hyper-V
One of the most important features in Microso Windows 2012 Hyper-V for I/O performance is the VHDX
virtual hard disk format, which provides storage for the guest OS. Tesng by Microso shows that VHDX
delivers nearly 25 percent beer write throughput than virtual hard disk (VHD) for both dynamically
expanding and dierencing disks.
VHDX Performance—1MB Sequenal Writes