|Did you read the information in the link I provided. Sector by sector copy will copy everything, including empty sectors. As you pointed out above the size will match the partition size and not be smaller.|
I really don't understand the use of a raw image but there must be one. Ghost and Acronis default to imaging only the data.
I assume the way the data is compressed is to use more of the slack space in each cluster. Somehow that data has to be tracked so you know how to properly reassemble it. So there is some overhead involved.
I am not sure about your file size above. I will tell you that you should be able to span multiple disks and that typically Windows OS files will compress about a third. So you should be able to get over 6GB of compressed data on one DVDR.
Just make a trial run. I buy single layer DVDR on sale for about 15 cents each in spindles of 50 or 100. At that price I don't worry about the use.
I use Ghost 2003 and have multiple partitions on my main hard drive. Each is imaged at different intervals. I have used both DVDR and CDR on the same image with no adverse affects. Ghost simply accepts whatever type of media you supply. I am not a fan of rewritable media. To expensive and many optical drives may have trouble booting to them.
As I stated before, DVDR is actually only about 4.4GB of actual storage space. The numbers vary slightly depending on weather the disk is DVDR+ or-.