I’ve been using Dropbox since it first came out and I always knew it ran on Amazon S3. Not anymore. Apparently, two and a half years ago, Dropbox began to build their own storage infrastructure.
Vice President of engineering, Aditya Agarwal:
Just getting the bits out of Amazon and into other data centers was an epic task. Digitally moving petabytes of data from one machine to another isn’t exactly on the same scale as downloading a few songs for your laptop. Even the fattest Internet pipes only have so much bandwidth. Transferring four petabytes of data, it turned out, took about a day.
You can read the full article on Wired.