Quick Fixed VHD Creation Tool

re: Quick Fixed VHD Creation Tool

Aitor Ibarra — Thu, 26 Mar 2009 18:27:51 GMT

Ben - many, many thanks for this. Most of my fixed vhds are created on "virgin" disks - meaning there's no data on them, so need to over-write empty space with zeroes. This will slash provisioning time without the compromise of using a dynamic vhd.

re: Quick Fixed VHD Creation Tool

Hyper User — Thu, 26 Mar 2009 20:07:06 GMT

This is a great tool. Would this feature be available in a future version of Hyper V Manager? Say as an option with the necessary warning?

re: Quick Fixed VHD Creation Tool

Gavin Raymen — Wed, 08 Apr 2009 01:54:52 GMT

Awesome. This will be a massive timesaver.

re: Quick Fixed VHD Creation Tool

Jim L — Fri, 10 Apr 2009 01:50:56 GMT

Hi,

I posted this on the vhdtool webpage:

"I just tried this tool, using the command line above for creating a 10GB fixed VHD. On the host, I got a 10GB .vhd. I use a partitioning tool, Bootit NG (http://www.terabyteunlimited.com) which can boot from floppy and do things like resizing partitions. So, I pointed a VMC to the new VHD, and booted with a Bootit NG floppy image, which took me to Bootit NG. I had intended to use Bootit NG to resize a partition, but when I look at the VHD in Bootit NG "Partition Work", instead of a 10GB "HD0", I had an ~130GB "drive"! Is it because this tool doesn't zero out the data and so Bootit NG is getting confused about the partition sizes? Any ideas about why this might be?"

I also posted about the problem on Terabyte Unlimited's support newsgroup, and the response I got was:

"BING just uses what the BIOS reports."

so, apparently, with a VHD created using vhdtool, the VPC guest's BIOS is reporting, in my case, 130GB.

Any idea why that might be and how to work around the problem?

Thanks,

Jim

re: Quick Fixed VHD Creation Tool

Jim L — Fri, 10 Apr 2009 02:25:58 GMT

Hi,

I just tried it again. I used this command to create the VHD:

P:\foo>VhdTool.exe /create "p:\foo\foo.vhd" 10737418240

Status: Creating new fixed format VHD with name "p:\foo\foo.vhd"

Status: Attempting to create file "p:\foo\foo.vhd"

Status: Created file "p:\foo\foo.vhd"

Status: Set the file length

Status: Set the valid data length

Status: VHD footer generated.

Status: VHD footer appended.

Status: VHD header area cleared.

Status: Complete

P:\foo>dir

Volume in drive P is WD120GB

Volume Serial Number is EC15-9FC3

Directory of P:\foo

04/09/2009 06:52 PM <DIR> .

04/09/2009 06:52 PM <DIR> ..

04/09/2009 06:52 PM 10,737,418,752 foo.vhd

So, the foo.vhd is 10GB on the physical drive.

When I boot into the BING from floppy, BING shows HD0 with an empty area of 130552 MB of free space.

If I go to the VPC guest's BIOS at boot, it says:

Device : Hard Disk

Vendor : Virtual HD

Size : 136.9GB

LBA Mode : Supported

Block Mode: 128Sectors

PIO Mode : 4

Async DMA : MultiWord DMA-2

So, it definitely looks like the guest's BIOS thinks that it's a 130GB drive.

Any ideas how to fix this problem?

re: Quick Fixed VHD Creation Tool

Jim L — Fri, 10 Apr 2009 06:28:24 GMT

Hi,

I created a smaller VHD so that I could see it in a hex editor:

P:\foo>VhdTool.exe /create "p:\foo\foo.vhd" 13631488

Status: Creating new fixed format VHD with name "p:\foo\foo.vhd"

Status: Attempting to create file "p:\foo\foo.vhd"

Status: Created file "p:\foo\foo.vhd"

Status: Set the file length

Status: Set the valid data length

Status: VHD footer generated.

Status: VHD footer appended.

Status: VHD header area cleared.

Status: Complete

and then I used VPC2007's VHD wizard to create the same size VHD, foo1.vhd.

Looking a foo.vhd vs. foo1.vhd, it looks like the "Disk Geometry" in the footer is different:

foo.vhd (created by vhdtool.exe):

0x34D3103F

foo1.vhd (created by VPC2007 wizard):

0x01870411

Why is the "Disk Geometry" in the footer in the VHD created by vhdtool.exe different?

re: Quick Fixed VHD Creation Tool

Jim L — Fri, 10 Apr 2009 07:05:00 GMT

Hi,

BTW, I just tried another test, creating a 5GB+ VHD, then installed Win2K. Disk Management (in Computer Management) sees Disk 0 as a 127.49GB drive!!

So, it's not just Bootit NG that thinks that the vhdtool-created VHD is a 130GB drive... Win2K Disk Management also sees a 130GB drive :(...

re: Quick Fixed VHD Creation Tool

JIm L — Fri, 10 Apr 2009 07:08:28 GMT

Hi,

I'm wondering, has anyone actually used vhdtool.exe to create a VHD, and then installed, say, Win2K on the VHD, and had Win2K report the "correct" disk size?