Can't read VDI data files

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Can't read VDI data files

Postby cefmel » 22. Jan 2012, 03:45

I have some software (PowerISO) that claims to be able to read VirtualBox Virtual Disk Image Files. I'm running a Windows 7 home edition 64 bit Host with a DOS guest OS. When I try to read the data VDI file that the DOS guest uses, I get an error saying that the format is incorrect. Does anyone know to get files out of the VDI file from the host? I've given up for now trying to network the two systems, so this is the only way I can think of to get information out of the guest DOS operating system. Any help is greatly appreciated.
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Re: Can't read VDI data files

Postby allpoints » 22. Jan 2012, 04:38

you're asking about PowerISO errors?
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Re: Can't read VDI data files

Postby cefmel » 22. Jan 2012, 04:51

I'm new to Virtual Box so I'm not sure what this means. I tried entering this into a command line with the path to the Virtual Manager and I got a dialog box that appeared for 1 second and then disappeared.
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Re: Can't read VDI data files

Postby cefmel » 22. Jan 2012, 04:53

Hi allpoints. I'm just trying to get information out of the .vdi files. I tried using PowerISO to look at the .vdi files but I get an error from PowerISO that the format is not supported.
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Re: Can't read VDI data files

Postby allpoints » 22. Jan 2012, 05:05

sorry about my edit...I realized it wasn't the time for that command...

you may have to rely on luck for PowerISO help in a VBox forum...good luck! :lol:




have you tried using your .virtual disk image to create and run a VBox virtual machine yet?

it should take about 10 minutes to dive right in and get started, and there are a lot of tutorials on creating a VM from a .vdi that show every screen you'll encounter. The main difference is that with a .vdi, there's less steps. 8)
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Re: Can't read VDI data files

Postby cefmel » 22. Jan 2012, 10:13

Hi allpoints, I'm not sure what you mean by using a vdi file to create a VM. Are you saying that instead of booting from an ISO file you can boot from a vdi file? If so, what would be the advantage. I still have no way of reading a vdi file from the host, thus there is no way for me to get files from the guest virtual hard drive. To me, the vdi file is like some black magic box that can't be broken into from the outside, you can only see it from the inside on the guest OS. I have a DOS application that runs on the VM DOS system and creates small files that I need to take off this computer, to use them on an older computer that runs an engraving machine. I believe these small output files are in the vdi file since I believe it is the virtual hard drive for the DOS VM. I'm trying to find a way to export what ever files are in the vdi if possible.
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Re: Can't read VDI data files

Postby Etepetete » 22. Jan 2012, 10:34

Hi cefmel, I think I understand your problem, you have a DOS VM and as such no Guest additions and as a result no shared folder.

If you have another VM (Windows, Linux), attach the DOS VDI to it as a second HDD. Start the VM access the second HDD and copy the files you need to the shared folder.

Edit: You also have a windows 7 host. You can try the "VBoxManage clonehd" command to convert the VDI to a VHD and try mounting it in Windows 7.
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Re: Can't read VDI data files

Postby allpoints » 22. Jan 2012, 12:47

cefmel wrote:Hi allpoints, I'm not sure what you mean by using a vdi file to create a VM. Are you saying that instead of booting from an ISO file you can boot from a vdi file? If so, what would be the advantage. I still have no way of reading a vdi file from the host, thus there is no way for me to get files from the guest virtual hard drive. To me, the vdi file is like some black magic box that can't be broken into from the outside, you can only see it from the inside on the guest OS. I have a DOS application that runs on the VM DOS system and creates small files that I need to take off this computer, to use them on an older computer that runs an engraving machine. I believe these small output files are in the vdi file since I believe it is the virtual hard drive for the DOS VM. I'm trying to find a way to export what ever files are in the vdi if possible.


here's an example for a prebuilt linux .vdi, but it's applicable to any host OS:

http://www.oracle.com/technetwork/middl ... 365540.pdf

Of course, your vm name, ostype, and memory requirements will be different, but the section about "Use existing hard disk" is the important part. You don't need to create one if you already have a suitable .vdi or .vmdk to use.
If the .vdi has a boot sector it should be bootable, but we can't tell yet.
(booting and running another OS on VBox is what I mean by "Create a VM"...the running OS is called a 'Virtual Machine'...sorry about the new vocabulary... :D )

After we get your DOS VM running you can likely create a shared folder so programs outside VBox and the VM can have access to the output like you want.
Some questions though:
Where did you get the .vdi image? Is it supposed to result in a functioning VM? Or is it intended to be plain storage for an existing VM you already have running?

The Tux Demo .vdi in the link I posted is like a little hard drive with an .iso installed on it, just like a physical hard drive with an OS installed on it.
Is this basically what we're dealing with here, something meant to be a standalone OS? Or is it a case like Etepetete described, where you are expected to attach your DOS .vdi to an existing Windows/IBM VM?
I asked in two different ways because you need to be clear on this, as it makes a difference in how we proceed.


If you just don't know at this point, I'd suggest trying to start the .vdi in VBox by applying the tutorial I linked. Either by success or failure, it will take very little time to ascertain what's going on that way.



tl;dr: Go ahead, pull the trigger!

On edit: looks like you are making some headway in the Allgemeine Diskussionen forum, but the nuances are beyond my slight grasp of Deutsch...
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Re: Can't read VDI data files

Postby cefmel » 22. Jan 2012, 18:10

Wow, thanks a lot for all the responses, this should keep me going for a while. I can't work on this today but it looks promising. I have an old copy of Windows 98 - would that work?

Thanks again for all the help.

Long live DOS,

cefmel
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Re: Can't read VDI data files

Postby Leak » 22. Jan 2012, 21:45

cefmel wrote:Wow, thanks a lot for all the responses, this should keep me going for a while. I can't work on this today but it looks promising. I have an old copy of Windows 98 - would that work?

There's no guest additions for Windows 98 either. Do yourself a favour and just grab any recent-ish Linux distro, install it in a new VDI, add the guest additions and your existing VDI then use VirtualBox' shared folder feature to copy your files onto the host.
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Re: Can't read VDI data files

Postby cefmel » 23. Jan 2012, 03:31

OK, I assume there is no problem using shared folders for Linux with the DOS vdi file. I'll do what ever it takes, I love adventures and I've never seen a Linus OS before so that should be interesting.

I can't over emphasize my appreciation for your help,
Rock on my friends,
Cefmel
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Re: Can't read VDI data files

Postby cefmel » 23. Jan 2012, 20:29

Problem solved - I have gotten PowerISO to work now on VDI drives and VDH drives. I don't know what the problem is but it has trouble mounting some of the VDI files I created earlier. It's possible that maybe I copied them before I realized that you can't copy these VDI files without corrupting them.

Thanks for all the help,
cefmel
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Re: Can't read VDI data files

Postby mpack » 24. Jan 2012, 17:59

cefmel wrote:It's possible that maybe I copied them before I realized that you can't copy these VDI files without corrupting them.

You certainly can copy them (with the host OS I assume you mean) without corrupting them. The only thing you can't then do is mount the copy in a VirtualBox VM, until the UUID field in the header has been changed, otherwise it conflicts with the original. However for the purpose of reading with PowerISO the copy is just as good (I'm not a PowerISO user, I'm taking your word for it that VDIs are supported - and not only fixed size VDI) [*].

Of course another classic error would be to take the base VDI of a snapshot chain and copy/clone that. Then you're into multiple error scenarios, one possibility of which is PowerISO not finding a filesystem on the drive, because the filesystem was added post-snapshot.

[*edit] I just downloaded the PowerISO trial and gave it a go, and it does indeed seem to be able to open and view the contents of dynamic VDI files. Of course it will only support a limited number of possible guest filesystems: the Windows host version certainly supports FAT and NTFS guests, but does not seem to support Linux (EXTx). I did not test any others. This is useful information, so thanks for bringing it to my attention.
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Re: Can't read VDI data files

Postby sarahsolen » 11. May 2012, 21:06

I just wanted to post and say thank you to the person who mentioned PowerISO. I have a VDI file that has been corrupted and even trying to recover with the boot disk, etc. I was getting nowhere. Most of my files were in a shared folder so they were safe, but there were a couple of folders that contained application data that I didn't want to lose. I was able to use PowerISO to get my files off. I couldn't get the PowerISO mac os x version to work on my mac so I just installed the windows version on another computer and accessed the vdi file over the network. Hope this helps someone else who is pulling out their hair trying to recover some files.
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Re: Can't read VDI data files

Postby BillG » 12. May 2012, 02:56

I have always found that the easiest way to read files from a .vdi (or any other virtual hard drive) which will not boot is to attach it as an additional drive to a working virtual machine. No additional software required.
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