f0b8204072
As discussed at our nova meetings, reorganize the juno specs into three directories: - proposed: things proposed which weren't approved - approved: things we approved but didn't implement - implemented: things approved and implemented The first I suspect is the most controversial. I've done this because I worry about the case where a future developer wants to pick up something dropped by a previous developer, but has trouble finding previous proposed specifications on the topic. Note that the actual proposed specs for Juno are adding in a later commit. Change-Id: Idcf55ca37a83d7098dcb7c2971240c4e8fd23dc8
2.8 KiB
Add differencing vhdx resize support in Hyper-V Driver
https://blueprints.launchpad.net/nova/+spec/add-differencing-vhdx-resize-support
Differencing VHDX images can be resized, unlike differencing VHD images. Even so, the Nova Hyper-V driver currently does not support this.
This feature is required for resizing existing instances which use CoW VHDX images and also in order to resize the root disk image when spawning a new instance.
Problem description
Currently, when using the Hyper-V Nova Driver and differencing (CoW) VHDX images for the instances, the differencing image will not get resized according to the flavor size. Instead, the VM root image will keep having the same size as the base image used when spawning a new instance.
Also, when trying to resize such an instance, not only that the disk image will not get resized, but this will actually raise an exception as currently the method which gets the internal maximum size of a vhd/vhdx does not support differencing images.
Proposed change
The solution is simply passing the desired size when creating a new differencing vhdx image. Not passing it will result in the new disk having the same size as the base image.
Also, it is required that the method which gets the internal maximum size of a vhdx to lookup the parent disk and return the according size instead of raising an exception.
Alternatives
None
Data model impact
None
REST API impact
None
Security impact
None
Notifications impact
None
Other end user impact
None
Performance Impact
None
Other deployer impact
None
Developer impact
None
Implementation
Assignee(s)
- Primary assignee:
Work Items
Add a "size" argument to the create_differencing_vhd method.
Adapt the vmops module to specify the new size only if resize is required when booting a new instance using CoW vhdx images.
Lookup for the parent image and get the according size when getting the maximum internal size of a vhdx.
Adapt the vhdutils according methods in order to have the same method signatures and keep consistency.
Dependencies
None
Testing
Testing this feature will be covered by the Hyper-V CI.
Documentation Impact
None
References
Official VHDX format specs: http://www.microsoft.com/en-us/download/details.aspx?id=34750