Unable to boot Windows from physical partition

Discussions about using Windows guests in VirtualBox.
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DalekClock
Posts: 9
Joined: 5. Sep 2007, 19:50
Location: Bracknell, UK

Unable to boot Windows from physical partition

Post by DalekClock »

I'm trying to boot my Windows partition under Virtual Box, except when I start it up I just get:

Code: Select all

GRUB loading...
Error 21
What is error 21 and how is GRUB involved if it isn't even on that partition?
I'm in the high-fidelity, first-class traveling set and I think I need a lear jet.
Ingo
Volunteer
Posts: 731
Joined: 22. Aug 2007, 10:13
Location: Germany

Post by Ingo »

Please go to
http://www.google.com
and in the first line insert:
grub error 21
and press enter.
DalekClock
Posts: 9
Joined: 5. Sep 2007, 19:50
Location: Bracknell, UK

Post by DalekClock »

I searched and it found something saying that error 21 is "Cannot find disk". I'm guessing it's referring to the Linux partition, but how is that involved and how do fix it?

Also, try to be a bit more helpful than "just Google it". People would rather have a specific solution to their problem that search engines probably won't find for them.
I'm in the high-fidelity, first-class traveling set and I think I need a lear jet.
LFS-Nr-3305
Volunteer
Posts: 116
Joined: 8. Jun 2007, 11:36

Post by LFS-Nr-3305 »

Look, some people here are from innotec and maybe are interested in helping people use the product (I don't believe they are paid for browsing all the questions, however...), but most are, like me, normal users from outside trying to learn from the problems and answers of others, and to be helpful if they find a question which they believe they can understand or even resolve.
So, if one of us other readers has the impression a question is posed which has been answered elsewhere frequently, he may try to direct you to find a solution, for example by mentioning google.
If you tried that before, too bad that you have a problem which is not so easily solved as was assumed. But a lot of less experienced users have no idea how to do research so I am sure that a hint to use google has been meant helpful.

To the grub question. Grub is a bootloader and, depending how it hat been installed, may sit in one part of the HDD where all systems, Windows, Linux, every other system, looks first. One earlier system contained all the information in this tiny place (Lilo), but Grub then looks in a place with a table (/boot/grub/menu.lst or so) which the user or the original installation programm of a Linux distribution can leave all the information, from which partition(s) to boot or to offer a multi-boot menu.
I do not know Windows very well but I recently found out that Windows2000 uses the same system. There the table is called boot.ini or similar.
On your PC, obviously, grub has been installed but the table has been deleted, the HDD renamed, the menu.lst changed, whatever. In your question, you gave no information how this could be. If you do a new installation or something like fdisk /mbr under Windows, the Master Boot record (the small, central information storing place of your HDD) will be written new (but be cautious, because afterwards you will not be able to boot the other systems; possibly your boot menu will have disappeared!). But with Grub it is quite easy, too, to enter the information from which HDD it should boot WITHOUT new installation. Some experience is needed for this. Linux users would boot from a "live" CD, then make the partitions writable and then simply edit the menu.lst or make a new one.

So I can not explain to myself what has gone broken in your linux installation. Are you saying that if you do not try to boot Windows, your Linux will boot normal?

Now to what you are saying, that you are trying "to boot your windows partition under Virtual Box". Did I understand this correctly - that you did not install a virtual machine and install a copy of windows in it, but you are trying to boot a windows which is on a partition outside of Virtualbox and probably has been installed before? It is in the manual, and it has been mentioned in dozens of other threads of this forum (the last one I read only yesterday) that this is not possible. So maybe you could browse through the older threads and the Virtualbox manual (UserManual.pdf in your Virtualbox directory on /opt) and maybe find some informations broader than a short reply to your question, which in itself could not give sufficient informations for the real problem, whatever that may be.

Good luck, and maybe you could give some more information. I am sure more competent people than me will find a solution then.
Ingo
Volunteer
Posts: 731
Joined: 22. Aug 2007, 10:13
Location: Germany

Post by Ingo »

DalekClock wrote:Also, try to be a bit more helpful than "just Google it". People would rather have a specific solution to their problem that search engines probably won't find for them.
Hi DalekClock,
sorry for my impoliteness but it was meant a little bit ironic to say what LFS-Nr-3305 explained.
(@LFS-Nr-3305: thank you for your detailed explanation).
It is always the same problem with this medium, you couldn't see my smiling face when I wrote my quote :-))

Let me ask some questions to your problem getting the error message from grub "Cannot find disk".
- what operating system is your host (I suppose any **ux because grub is involved)?
- when you start the Windows installation in a virtual machine the error comes up. A normal Windows installation does not use grub. Why does the error message appear?
- do you installed Windows on a virtual disk (*.vdi) or do you use raw hard disk access from a guest to a physical partition with your Windows?
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