1,17 GB on a standard pressed CDROM ?!

Hi, I hope you don’t mind posting me this thread here.

I’m pretty puzzled. I got a new CD from Microsoft with MSDN-Versions of Windows 2000 and Win2k Server.

The complete file system on that CD contains 1,17 GB of user data, not compressed. If you copy it to HDD it will be exactly that size.

However, ISO Buster tells me the following:

  • 1 Track
  • 1 ISO 9660 Session
  • Mode 1
  • Size LBA: 249.452
  • Size Bytes: 510.877.696

there are no other tracks or filesystems included.

Ok, physically I have 486 MB on that CD, this looks normal. But how can it be that this file system can contain that huge amount of user data?!?

I thought of Mode 2 Form 2, but ISO Buster says, it’s just simple Mode1.

And Subchannels can’t hold so much of extra information (and if they could, how should it become possible to put user data there?!).

Could anyone of you imagine, what’s going on here? If you need more info, please feel free to ask.

Thanks a lot!!

It’s probably that there are many duplicated files. In the file name table there are duplicate file names (in different directories) referring to duplicate references to the same file on the CD. When you copy the files, Windows will copy those files more than once.

A nice example is the MSDN upgrade 3 in 1 Windows 2003 Server CD. Together the total file size is about 1GB when copied to HDD, but the total used space on the CD is only about 580MB. It’s easier to imagine in this case, because each version of Windows 2003 Server contains many of the same setup files.

Files that are common to each, are aliased, using the CDIMAGE utility (Microsoft private, but leaked everywhere)
http://www.tech-hints.com/xp.html - some multiboot hints

Thank you very much, this sounds reasonable to me. I just did not know, that ISO9660 supports aliasing of files in the directory table. But this seems to prove it. Well, and I hoped to find the ultimate storage expander… :wink: