Support for large ISO images in Virtual Server SP1 Beta

Support for large ISO images in Virtual Server SP1 Beta

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One of the new features / bug fixes in the Virtual Server SP1 Beta release is that we now support the use of ISO images that are over 2.2GB in size (yay!). 

A number of people have wondered why we supported ISO images up to 2.2GB in size but not higher - the reason is that prior to Virtual Server Service Pack 1 we never actually officially supported the concept of 'DVD ISO Images'.  All ISO images that are under 2.2GB in size are really just very large CD ISO images.

In the mean time - if you are using Virtual Server RTM or Virtual PC you can work around this issue by using a virtual CD program on the host computer to mount the ISO and then map it to the virtual machine (I prefer Daemon Tools: http://www.daemon-tools.cc)

Cheers,
Ben

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  • > we never actually officially supported the
    > concept of 'DVD ISO Images'. All ISO images
    > that are under 2.2GB in size are really just
    > very large CD ISO images.

    Three questions here.

    I think it was for a Longhorn preview some time ago, I downloaded an ISO image for which the MSDN page was itself confused over whether the image was a CD image or a DVD image. I think I was using Nero 5.something at the time and it refused to burn either a CD or DVD. No matter which kind of media I put in the drive, Nero said the image was invalid. Later I installed VPC 2004 and it loaded the image into a virtual optical drive of some sort. So Nero was telling the truth, the image really was invalid for all kinds of physically existing media?

    VPC 2004 SP1 still has trouble with real DVDs too, when the physical drive is captured. The guest's Windows Explorer was showing the virtual drive as a CD-ROM instead of DVD-ROM, and it was failing to execute the program on the physical media. It is necessary to use the real PC to read all files from the media to a folder on the real hard drive, share the folder with the guest OS, use the guest's Windows Explorer to copy all files from the shared folder into the virtual hard drive, and then execute the program. An example was a Visual Studio 2005 beta. Is there any better way to do this?

    And now a non-question. With an image that was nearly 4GB in size, without burning it to a DVD, VPC 2004 SP1 gave an error message almost exactly as you know, but the message is very highly misleading. It said that the size of an ISO image must be at least 2MB and must be a multiple of 2048. I thought that the download had been corrupted and was planning to repeat the download, but for some reason I searched on Google to see if it was a known problem. It was. But one of your colleagues thought it was because VPC 2004 was doing signed arithmetic and figuring that nearly 4 GB was nearly -300MB or thereabouts, less than the +2MB required minimum. So I burned it. For some reason that image burned instead of being diagnosed as an invalid image. Anyway, you are saying it wasn't a bug doing inappropriate signed arithmetic, but it was an intentional 2.2GB restriction? What was the purpose?
  • At its (VS, and especially VPC) inception, there were almost no DVD ISO images. In fact, when I was trying to test this back in 2003, I was unable to find any that were over 2GB in size and back then, there were very few, and IIRC, no apps to create custom DVDs to burn.
  • Monday, June 13, 2005 7:46 PM by Steve J

    > At its (VS, and especially VPC) inception,
    > there were almost no DVD ISO images.

    Hmm, you might be right. MSDN had some images posted for download in 2002 but the biggest ones I can find were around 1.5GB. Bigger ones were self-extracting .exe files that apparently extracted to the complete structure of the corresponding DVD, instead of expanding to an ISO image.

    That doesn't affect my questions though...
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