I downloaded the freeBSD isos and burned them to DVD. But, I have to confirm the burn was OK. How can I run an md5 on the actual resulting dvd? I ran the md5 on the images with no problem as seen below: Using md5sum from macports Justins-MacBook-Pro:SONY8G justin$ md5sum 8.0-RELEASE-ia64-dvd1.iso 6b8df7fb34d5960ecf91a291926a1e6f 8.0-RELEASE-ia64-dvd1.iso and using the md5 command included with Snow Leopard Justins-MacBook-Pro:SONY8G justin$ md5 -r 8.0-RELEASE-ia64-dvd1.iso 6b8df7fb34d5960ecf91a291926a1e6f 8.0-RELEASE-ia64-dvd1.iso Obviously both are identical. Now if I try to run md5 or md5sum on the drive this is what I get: Justins-MacBook-Pro:~ justin$ md5sum /dev/disk2md5sum: /dev/disk2: Not a regular file Using the md5 command included with SL: Justins-MacBook-Pro:~ justin$ md5 -r /dev/disk2 d41d8cd98f00b204e9800998ecf8427e /dev/disk2 The above is incorrect, the drive doesn't make a sound so it obviously isn't checking through all the bits on the disc. I'm not sure what its doing, but it sure isn't md5'ing the entire disc. I'm paranoid about the burn being a bit off - these discs are going to be sent to the middle of nowhere where the internet doesn't reach - they have to be perfect. I can't really go into more detail. Plan B is ordering the discs - but I would like to know this in case I have to send another disc out that doesn't have a pressed copy available - such as data.