I began trying to backup my dvd collection to an external hard drive. I do this my making disk images(.iso) from the dvds. To do this I use disk utility > new image > save as dvd/cd master. Started with some Battlestar Galactica. First 6 disks of season 1 went fine. Next 3 disks of season 2 went fine. First disk of season 2.5 I get an input/output error about 75% through the process. Any ideas?
I think the issue is with your disk. If you have access to a spin doctor I would suggest that.
Since your trying to get it as an iso, MacTheRipper and Handbrake will not do this. You could try http://www.xilisoft.com/dvd-copy-mac.html .
You could also dd from the comand line. But this may be what disk utility already uses to create cd/dvd master copies. Just google this for syntax.
This could be a problem with the drive, or (more likely) a problem with the DVD. Perhaps there's a scratch on it, or maybe just a smudge. It's tough to say.
If you copy the files directly, you can still play it with VLC.