Information on FireWire Cables
Over the past few weeks, our support department has seen a spike in inquiries for purported software issues such as aborted writes or disk and tape drives simply disappearing from the FireWire bus that turned out to be simple cable-related problems.
Though it may seem unbelievable (or even improbable), it is possible for a FireWire cable to work with the rather relaxed asynchronous mode used by hard drive but be unable to reliably pass the more rigorous isochronous data required for backup streaming over FireWire.
Do not fool yourself into thinking that a cable is "good" because it managed to move some data to and from your host to an external disk. Due to mechanical wear on the connectors and wire, FireWire cables simply wear out. However, because of the error correction built into the data stream, functional failure may be gradual and intermittent. A prudent practice is to keep a new FireWire cable in storage for troubleshooting. If a problem is found, put that new cable into service, dispose of the suspect cable, and run a new backup.