Assuming: 50 million files, assuming 4x concurrency per CPU, taking 1 second each, would take approx 150 CPU days. Using just 10 machines it could be done in 15 days. This does not fundamentally seem like a massive project in terms of compute? If time per instance would go up factor 10x, if one would allow 30days execution, could be done by 50 machines. I think that most compute providers can do that (given some months notice)?