Re:Not hard (Score 4, Interesting)

The issue isn't the number of bytes per second, it's the number of distinct requests. The data is _way_ bigger than will fit in memory, and hard disks can only do 100-150 seeks per second so you need a lot of them to serve from disk. A naive implementation will go to disk many times for a single file, because filesystems aren't designed for this many small files. So this is really an issue of getting exactly the right stuff in memory so you can serve hot content from memory, and if you go to disk you seek exactly once instead of several times.