Linux guest images on Hyper-V fail to access local storage when using resized differencing VHDX disks

[Alessandro Pilotti]

Description of the issue

Create a differencing disk of a Linux image VHDX (any Linux distro with LIS), resizing it in the process (without resizing the base disk)
Create and boot a VM with the disk attached on the IDE controller

During boot the hv_storvsc module will start logging repeatedly the following message:

hv_storvsc vmbus_0_1: cmd 0x28 scsi status 0x2 srb status 0x4

(along with various I/O errors on sda1).

The machine manages to boot eventually after a long delay.

The following PowerShell script can be used to reproduce the issue:
http://paste.openstack.org/raw/110766/

Tested on: Hyper-V 2012 R2 and with various Linux guests.

Workaround:

Apply the same technique used for VHD disks, where a copy of the base image is resized before the differencing one is created.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/122195

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/122195
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=1f26df24a63624545cfe67745af53623947a6d28
Submitter: Jenkins
Branch: master

commit 1f26df24a63624545cfe67745af53623947a6d28
Author: Lucian Petrut <email address hidden>
Date: Thu Sep 18 11:55:56 2014 +0300

    Fixes differencing VHDX images issue on Hyper-V

    When using differencing vhdx images, one will be created pointing
    to the base image when a VM is spawned. This image will be created
    having the according flavor size.

    In this case, due to a Win32 API issue, the image is not generated
    properly.

    Simply creating the root image with no size specified and resizing
    it afterwards fixes the issue.

    Change-Id: I7bb46a63d4c2a06ed6f63c839461cbbc1abffa65
    Closes-Bug: #1370531