[vbox-dev] Fwd: VHD not readable by Hyper-V

[Huihong Luo]

I found the vhd bug on vbox implementation. vbox mistakenly sets parent locators ("wi2r", etc.) for base vhd image. If setting these fields to zeros for base image, Hyper-V is happy. Should be very easy to fix, if you need the code diff, let me know

VBox The MS spec states:





Parent Locator Entries

These entries store an absolute byte
offset in the file where the parent locator for a differencing hard disk is
stored. This field is used only for differencing disks and should be set to
zero for dynamic disks. 




--- On Tue, 10/13/09, Huihong Luo <huisinro at yahoo.com> wrote:

From: Huihong Luo <huisinro at yahoo.com>
Subject: [vbox-dev] Fwd:  VHD not readable by Hyper-V
To: "vbox-dev at virtualbox.org" <vbox-dev at virtualbox.org>
Date: Tuesday, October 13, 2009, 6:49 AM



Sent from my iPhone
Begin forwarded message:

From: Huihong Luo <huisinro at yahoo.com>
Date: October 13, 2009 6:35:42 AM PDT
To: Shu Wu <superwushu at gmail.com>
Subject: Re: [vbox-dev] VHD not readable by Hyper-V

No problem with vpc, vbox also understands vhds from hyper-v

It is just that hyper-v doesn't understand vbox's vhd 
Sent from my iPhone
On Oct 13, 2009, at 2:27 AM, Shu Wu <superwushu at gmail.com> wrote:

Can your VHD disk be read by Virtual PC or Virtual Server? It seems
that Hyper-V and Virtual-PC share the same vhd format. One year ago I
wrote my own program to generate a vhd file and make it to be accepted
by Virtual PC, just following the official vhd specification. But I
haven't tested it on Hyper-V.


Cheers,


Wu Shu

2009/10/13 Klaus Espenlaub <Klaus.Espenlaub at sun.com>

Huihong Luo wrote:


None of vbox created vhd disk files are readable by 2008 Hyper-V.

 This is the error: "The file or directory is corrupted and unreadable"

 I am debugging through the code, trying to change Footer info, such as version, creator OS, checksun, etc., to see it can correct the error.

 If you know what might be wrong, pls post




We only know what Microsoft documents in their VHD format spec, which we believe to have correctly implemented. However as usual those specs are incomplete and not really precise, so there's plenty of room for different interpretations.




Klaus





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