I use a number of different online backup services:[Dropbox](http://db.tt/bl7yQBc)[^fn1] and [SpiderOak](https://spideroak.com/)[^fn2] for my current working files, [iTunes Match](https://www.apple.com/itunes/itunes-match/) for my music collection. and [Crashplan](http://www.crashplan.com) for most other files. There are certain things, however, that I want to have in the cloud and be able to access from my other computers[^fn8] and from iOS devices, but–since I access them so infrequently–that would just clog up my Dropbox folder. Now, I put copies of all of those things in my [Bitcasa](http://bitcasa.com) cloud drive.
Bitcasa bills itself [as an external hard drive in the cloud that never runs out of space](https://www.bitcasa.com/how-it-works) and that is exactly how I use it. When the Bitcasa help program is running, you get a new drive in your sidebar that you can use just like any other external hard drive. The “magic” comes in how Bitcasa handles the copying of things to the drive. Basically, it appears that Bitcasa keeps a local cache on your drive[^fn3] that serves as the intermediate destination for things you are copying to the Bitcasa cloud drive. [^fn9]
In theory, this caching mechanism should allow standard OS X copy operations to work just fine. I found that for larger files and directories with a lot of files, however, I had much better luck using [Chronosync](http://www.econtechnologies.com/pages/cs/chrono_overview.html) to sync things to my cloud drive[^fn4]. For anything that did not exhaust the cache, however, standard OS X copies worked flawlessly.
Bitcasa does have some minor flaws. The most annoying is that the helper program that keeps the cloud drive open seems to crash every so often. Also, there seems to be a strange bug with file permissions where files stored on the cloud drive appear in Finder’s “light grey / in-progress” state, but are actually fully accessible[^fn5]. My hope is that these issues get resolved in a future release of the helper program[^fn6].
All in all, Bitcasa does exactly what is says it is designed to do: give me an external hard drive in the cloud. It is not as effortless as Dropbox, and it lacks some of the power of Crashplan, but it allows me to put a ton of files in the cloud and access them easily from my various computer and iOS devices[^fn7]. If you have a similar use case that you are trying to fill, I would definitely recommend giving Bitcasa a try.
[^fn1]: Affiliate Link (The kind where my size goes up if you use it.)
[^fn2]: Traditional Affiliate Link
[^fn3]: You can configure the cache if you like, including the directory that it is stored in, and its size.
[^fn4]: I would assume something like rsync would work well for this too
[^fn5]: I am sure there is an actual name for this state, but I am not sure what it is
[^fn6]: The helper program has been updated pretty regularly so far. I hope that continues. Also, my use of Chronosync has minimized the impact of the helper program crashes
[^fn7]: Bitcasa’s iOS app is kind of basic, but it does what I need it to do: give me access to my files
[^fn8]: The “multiple computer” requirement is why I cannot use Crashplan for this usecase.
[^fn9]: If the size of the stuff you are copying to the cloud drive is smaller than the cache, then the copy operation completes and the stuff is uploaded to the drive in the background. If the copy operation fills up the cache, the operation “holds” until things get uploaded to the cloud to free up space in the cache and then continues copying to the cache as space becomes available.