When you are using Boot to VHD you must have enough capacity on the underlying disk to fully expand the VHD. If you do not have enough capacity you will get a blue screen (aka Screen of Death). If you have this problem, try booting to a windows 7 or windows Server 2008 DVD. When you get to the first screen (asks for keyboard) press Shift-F10 to drop to a command prompt. Look for the underlying drive…
etc… until you find the underlying drive. Once you find the drive, make sure the VHD file is not read only using the attrib command
If there is an “R” to the left of the file, you will need to change it using the following command…
Attrib e:pathFileName.vhd –R
Why would it be read-only? Looks like windows may mark it as read-only if a boot fails due to out of disk space? If it was not read-only, look for files on that physical drive you can delete (you may also want to have an extra USB drive plugged in so you can move the files to that USB drive instead of deleting).
Using Diskpart you can (usually) mount the VHD to manipulate the contents of the VHD. You can confirm that the capacity available on disk is the problem. If you cannot mount using disk part (you get “access denied” message)
Commands to mount… from the command prompt
This will launch DiskPart utility. You will need the drive letter, path and filename of your VHD file. you can get this by doing a series of dir commands as indicated above. replace the drive, path and filename of your vhd file in the command below. You can eliminate the path if it is on the root of the drive… At the DISKPART> prompt…
Select VDISK FILE=E:MyPathYourFileName.vhd << This opens the VHD (full drive and path to the file are required)
LIST VDISK << This lists the drive. The * means it is selected
ATTACH VDISK << if you get Access is denied the disk cannot be expanded
Exit << Exit from diskpart utility
If you have confirmed you cannot mount the disk, you will have to change the size of the vdisk or move some files off the underlying disk to get the machine to boot.
Another Tip… You can open two (or more) command windows at the same time by clicking on the background installation screen and pressing Shift-F10 again. This way you can be at a command prompt and in diskpart at the same time.
Yet Another Tip… You can run bcdedit from the command prompt to list all all of the boot configuration data which may help you find the drive and path of your vhd.
rainer30 Aug 2011 7:19 AM
I have a question for really experts.
I boot directly from vhd (windows 7 ultimate) without any other system installed. I divided my hdd 320 gb into two partitions/volumes 100 gb and 197 gb
(remaining place 23 gb may be used by fat). the vhd was set to (i do not remember in detail) – i think – to 97 gb. after some updates for windows the blue
screen of death appeared with “VHD you must have enough capacity on the underlying disk to fully expand the VHD”. so i did a look on the facts. booting with
dos showed me the the vhd is about 18 gb large. i changed the two volume sizes with acronis disk director suite to 150 gb and 147 gb. after that the pc
started up normal without blue creen of death. then i opened the windows explorer and look at the free and occupied space of the started vhd and the two
volumes. and here i found something very interesting:
started vhd: free 78,4 gb /total 95,7 gb which compares to 100.000.000 mb which had to be set in diskpart
volume 1: free 47,5 gb / total 148 gb
volume 2: free 142 gb / total 149 gb
now my question: under dos the vhd only occuppy 18 gb which expand after starting from it to the set 95,7 gb,. that is ok. but on volume 1, where the vhd
lies, the started vhd uses 100,5 gb (148-47,5=100,5)!!! and 100,5 gb is larger than my set 100 gb for volume 1. that should be the reason for the blue
screen. but what i not understand is:
why expand the vhd over 100 gb when there is only 18 gb occupied under dos. i expected that the vhd file expands when the 95,7 gb runs full, not that it
expands when nearly 80 gb are free in the vhd. can someone explain this because this is not the purpose of a vhd?
another questions is: where are the 4,8 gb, difference between 100,5 gb (if vhd is startet, occupied on volume 1) and the shown size of 95,7 gb of vhd in
windows explorer? or i misunderstood something or mismatch some figures.
if someone can explain me this facts this may help a lot of other people to set the size of the vhd more sensible.
with kind regards