Jungle Disk (https://www.jungledisk.com/ https://www.jungledisk.com/) is pretty much what the article describes: * Files are stored in a provider of your choic

Jungle Disk (https://www.jungledisk.com/ https://www.jungledisk.com/) is pretty much what the article describes: * Files are stored in a provider of your choice (current options are S3 and RackSpace) * Encrypted using a key stored locally * Looks like a local disk * Files are cached locally according to a set limit Unfortunately, the implementation is too sloppy. At least on OS X, the server is accessed using a local WebDAV server that proxies all of the file access. The WebDAV server is a piece of crap that was extremely slow, and would periodically, mysteriously drop its connection, which would cause Finder to stall and complain. (I reported this problem to the Jungle people, but they were not able to figure out the problem, even from the debug logs.) The caching does not work in practice. It seems to not support streaming -- if you try to access a file that is not in the cache, it will download the entire file before you can read a single byte from it. (Actually this is merely a hypothesis at this point: I tried using Jungle Disk for my MP3 library, but whenever I tried to play a non-cached file, I had to wait half a minute for the file to be downloaded. This problem may be because MP3 files often store their song metadata, which players like Spotify use, at the end of the file, and Jungle most likely does not support seeking into uncached files.) There is no reason why a service such as Jungle Disk could not work, but it's all in the implementation.