Cloned from launchpad blueprint https://blueprints.launchpad.net/nova/+spec/vhd-to-vhdx-conversion-in-hyper-v.

Description:

With users having more and more data being generated every day they may need to support large disks on their Virtual Machines over the cloud. The current VHD format in Hyper-V supports creating Virtual Machines up to 2Tb and Customer application data may grow larger than this. To overcome this we can convert the existing VHD to VHDX format.  VHDX supports up to 64 TB of storage. It helps to provide protection from corruption due to power failures by logging updates to the VHDX metadata structures. It also helps to prevent performance degradation on large-sector physical disks by optimizing structure alignment. 

To support this feature, all the VHD’s can be converted to VHDX format using root\Virtualization\v2 namespace. 

We can provide the same support in OpenStack which will support the following two use case
1.	 Nova Compute to convert an existing in-use disk.
2.	Also support can be provided in glance to convert the existing image from VHD to VHDX.


Specification URL (additional information):

None