Hi, I'm the "Oren Jacob" from the video. Rendering at that time was distributed across hundreds of CPUs in hundreds of Sun boxes in a renderfarm. The authoritative version of the film's data (models, animation, lighting, sets, shaders, textures, etc..) which was where all rendering pulled data from or verified that it had the most up to date versions, was stored on a single machine.
There were several backup strategies for that machine, but they failed. A few reasons are outlined elsewhere in this thread (running past the 4gig limit on tapes) but, if memory serves, other errors were also occurring that involved drives being out of space so error logging wasn't working properly.
Making matters worse, after our initial restoral, the crew came back to start working on the show and then, a few days later, we discovered that the restoral we thought was good was, in fact, not. So we had, in effect, split the source tree and now had a bad branch with a week of the crew's work on it, including animation.
There were several backup strategies for that machine, but they failed. A few reasons are outlined elsewhere in this thread (running past the 4gig limit on tapes) but, if memory serves, other errors were also occurring that involved drives being out of space so error logging wasn't working properly.
Making matters worse, after our initial restoral, the crew came back to start working on the show and then, a few days later, we discovered that the restoral we thought was good was, in fact, not. So we had, in effect, split the source tree and now had a bad branch with a week of the crew's work on it, including animation.
So we had to untangle the mess as best as we could, which was about 70% script based, and about 30% by hand. Further details are in my post on the Quora thread... (http://www.quora.com/Pixar-Animation-Studios/Did-Pixar-accid...)