Don:
That's the conclusion I came to as well. I think ShadowProtect is generating a vhd that qemu doesn't correctly recognize. The blktap vhd code does work with it, so that is what I am using for now. Thanks for your help.
Derry
-----Original Message-----
From: Donald R Laster Jr [mailto:***@dlaster.com]
Sent: Wednesday, July 30, 2014 1:17 PM
To: Derry Bryson
Subject: Re: [Qemu-discuss] Does QEMU support VHD images > 127GB? - #2
Derry,
As I was driving back from the office today I thought of something that might be the cause of your problem. Maybe QEMU is not recognizing the version of the header of your VHD image and is defaulting to a basic header version. If you can manage to get the header decoded you may be able to get more information and some better help than me. :-)
Don
Derry,
I did a search for VHD in the qemu 2.0.0 code and ./block/vpc.c seems to have these comments about the image:
// The visible size of a image in Virtual PC depends on the geometry
// rather than on the size stored in the footer (the size in the footer
// is too large usually)
bs->total_sectors = (int64_t)
be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
/* images created with disk2vhd report a far higher virtual size
* than expected with the cyls * heads * sectors_per_cyl formula.
* use the footer->size instead if the image was created with
* disk2vhd.
*/
if (!strncmp(footer->creator_app, "d2v", 4)) {
bs->total_sectors = be64_to_cpu(footer->size) / BDRV_SECTOR_SIZE;
}
/* Allow a maximum disk size of approximately 2 TB */
if (bs->total_sectors >= VHD_MAX_SECTORS) {
ret = -EFBIG;
goto fail;
}
and these:
uint16_t cyls;
uint8_t heads;
uint8_t secs_per_cyl;
In ./qemu-doc.texi it talks about a
"Specifies which VHDX subformat to use. Valid options are"
Don
---
Derry,
I would agree that Windows Server 2008 R2 would not have that problem. Is is possible to try manipulating the cylinders/heads/sectors that the image is presented with? Maybe the interface is looking at cylinder 0 information and thinking it is smaller?
What version of qemu are you running with? Qemu 2.1.0 rc3 is on the download page at http://wiki.qemu.org/Download .
Keep in mind, while I use qemu, I do not know the internals. Just mentioning things that some times get overlooked. The VMs I am using are still running with 1.4 and when I get the chance will be updating. I don't do anything fancy with them. So I am not rushed to change them.
Good luck.
Don
Post by Derry BrysonIt's Windows Server 2008 R2, so I doubt that is an issue. I think
it's a bug or limitation with qemu as qemu-img shows it as 127GB also.
-----Original Message----- From: Donald R Laster Jr
Derry Bryson Subject: Re: [Qemu-discuss] Does QEMU support VHD images
Derry,
The first thing I would consider is to check the OS you are using.
Some OSes won't see the larger drives without special drivers. And
with the size you are indicating I suspect that is the issue.
Don
Post by Derry BrysonWhen I attach a vhd file that is supposed to be 500GB, it shows up as
a 127GB disk. Is there some limitation in QEMU or am I doing it
wrong?
Thanks.
Derry Bryson Senior Software Engineer Highly Reliable Systems
*/Backup should be easy and affordable/* 775-329-5139 ext _* 129
_www.High-Rely.com_ <http://www.high-rely.com/>
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Donald R. Laster Jr.
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