mato1980 Posted November 1, 2012 Share Posted November 1, 2012 I recently bought a new Windows 7 operating system shipped on a DVD and wanted to make a backup copy of the disc. When I saved the contents of the DVD to my hard drive, the size of ISO file was exactly 3320903680 bytes. After I burned the iso file to a DVD-R disc, I tested to make another ISO file from the DVD I just created. The size of the new ISO file was 3320905728 bytes so it was 2048 bytes more than what I expected. I also made a test by burning it to a DVD+R disc but the results were same. Did I do something wrong? How can I burn a backup copy that would be exact the same as the original? Now if I would like to verify that the the burned DVD is correct, the hash would be different. Link to comment Share on other sites More sharing options...
LIGHTNING UK! Posted November 1, 2012 Share Posted November 1, 2012 3320903680 / 2048 = 1,621,535 sectors 1,621,535 is not a multiple of 16 (the ECC block size) and some drives will only burn in multiples of the ECC block size - therefore you get a few padding sectors on the end (in your case, just 1 was required). This is a drive thing and nothing to do with the program. Just use ImgBurn to verify the disc as part of the burn. You don't need to manually hash check anything because it will have already compared the disc to the image at sector/byte level. Link to comment Share on other sites More sharing options...
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