OT: Data corruption via USB2

riredale wrote on 8/20/2006, 10:15 PM
I'm in the process of switching from Retrospect to Acronis TruImage as my primary backup utility, and today I spent a bit of time over on the TruImage message boards.

Seems there has been a lot of frustration expressed over the fact that backing up to external drives over USB2 can be dangerous in the sense that if there is a single bit error over the span of a 20GB file collection, the entire backup is trashed.

Many of the respondents on that board mention that they can verify this by running an MD5 ("CRC-like") check on the original files, and then running a second check on the files after transfer over USB2. They've found lots of instances where a very large file changes. Significantly, they did NOT find any corruption if they used Firewire.

Since we're in a similar situation here with single files commonly measuring over 10GB, I suspect something similar could be happening here. But I wonder what a single bit error in a large m2t file would do. Hopefully there would just be a glitch of some sort in the image, perhaps lasting for 15 frames? I really don't know.

Comments

DCV wrote on 8/21/2006, 10:04 AM
I'm pretty sure it would amount to essentially the same as a dropout on a tape, as long as the file structure in the directory is intact. A single bit error is pretty insignificant though and I'd be surprised if MPEG2 couldn't roll right over it without you noticing much. MPEG2 is designed to be very fault tolerant.

John