Apple this week released Thunderbolt Firmware Update v1.1, which the company said addresses an issue with mid-2012 MacBook Pros not working properly with bus-powered Thunderbolt devices. But other Macs may be having similar problems with Thunderbolt storage.
For many months, posts on the Apple Support Communities have reported erratic performance with some Thunderbolt storage products and cables, including arrays from several vendors. Users say their drives often freeze up and can't complete tasks such as backups.
According to the frustrated posters, Apple points to the firmware of the storage arrays. Some users identifed electromagnetic interference as the problem and suggestions have included wrapping the Thunderbolt cables with aluminum foil.
One recent post said that the Internet connection was the problem. By moving the Thunderbolt cable and storage array across the room, away from the cable internet wire connected to a router, appearently solved the problem.
However, several recent posts suggest that the issue is with the iMac. When they plug their arrays into a MacBook Air, the problem goes away.
It's all very mysterious — until the release of the next Thunderbolt Firmware Update.