> packing up to an order of magnitude more storage into 4U

Where are you buying 40 TB hard drives? I'd love to get some ;-)

We actually don't claim these are 'state of the art', more 'state of the inexpensive'. You can buy faster performance storage servers, more redundant servers, etc. But I believe these are one of, if not the, lowest cost storage servers per GB. (And of course, open source.)

BTW, I'm a fan of Dropbox (use it personally) and, in general, think there is a ton of value in developers, organizations, and companies sharing what they've learned about storage. The better and lower cost it gets, the more interesting things other people can do with it, the bigger the industry, and the more everyone benefits.

(full disclosure - cofounder of Backblaze here)