MSDN SQL 2012 - DVD

So how did they do this?  In today's snail mail I received a physical shipment of SQL2012 on a DVD.  On that DVD are "Business Intelligence", "Developer", "Enterprise", "Enterprise Core", and "Web" versions of SQL2012.  This disk is formatted with 4.26 GB of space according to Windows.

Copied to a network location the files are roughly 24 GB in size.  So how did they fit that all on one DVD?  The disc is not blue-ray.  Is this a case of "de-duping"?

Needless to say I was surprised by the results.  The disk does not appear to be damaged in any manner.

I think we can have "hard link" (multiple file records refering to same physical file data) on isofs and UDF disks.

http://technet.microsoft.com/en-us/library/cc722145%28v=ws.10%29

Reduced image size due to "single instancing," which means that the file data is stored separately from the path information. This enables files that exist in multiple paths or in multiple images to be stored once and shared across the images.

@felix9: That's really clever.