DVD Disk Space Mystery

Hello All,

My company uses a DVD to rebuild or repair PCs. It was produced in-house, and has various driver packs and tools along with quite a bit of automation. Whoever made this DVD has long since left the company leaving me with a mystery.

Being a developer, I began to look at the way this DVD was laid out. While I was able to update the automation, this disk itself is puzzling. In Windows, the DVD reports itself as 4.6 GB, but when the contents were copied to my desktop, the folders contain 20.1 GB. There is no obvious sign of disk or file compression being used, but the disk held 20 gigs!!

Do you have any idea how this might have been done? MFT Pointers? Magic?

Thanks,

Quiver

Maybe the dvd is dual layered? Although, unless, I am mistaken 2*4.6 = 9.12.

That is rather strange. Are there a very large number of files on the disk? DVDs often have a smaller cluster size (i.e. the minimum unit of disk space a single file can use). On a standard NTFS partition a file is always at least 4KB in size.

It may also be a screwed up driver reporting the wrong size; but the maximum size of a DVD is 4 x 4.6GB (i.e. dual layer, double sided). So maybe it is magic :)

Thank you both for your replies.

The only thing I can figure is that resources are copied to the disk just once, but they appear in various directories for different setups using Master File Record pointers. It is just guess, but I cannot think of any other way this can be done.

The amount of files on the DVD is 127,834 with 2,065 folders and the total file sizes combine to be 21.1 gigs (22,749,818,880 bytes), though the disk reports just 4.6 gigs when the properties are examined. While I am sure there might be some type of error in these stats, I can tell you they appear in both Windows 7 and XP. Also, I pulled the entire contents off the DVD to rewrite the automation, but the file structure is so large, I cannot burn it back to a DVD. Oh, and the original DVD is single density which I can duplicate easily with normal burning software.

I wonder if some Linux tool has allowed this magic? Sure is odd!

Where is Sherlock Holmes when you need him? :sick:

Quiver

There got to be compression involved. For example, Windows 7 setup image is only around 2.5GB but a fresh installation of Win7 takes more than 10GB.
As in your case, don't copy the full contents of the DVD. Make an image of the DVD (.iso or .img) and use program such as PowerISO to open the image. You then can edit the contents. Once done, create a new disc from the modified image.

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Originally Posted by stanav

Make an image of the DVD (.iso or .img) and use program such as PowerISO to open the image. You then can edit the contents. Once done, create a new disc from the modified image.

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Clever idea! I will let you know how it works. Most of the work I needed to do was subtractive, anyway, so this might work very well.

Quiver