Nasuni Filer is a virtual machine front end that uses various cloud storage vendors as a back end, and presents itself to subscribers as a CIFS share, amounting to a network attached store/fat hard drive in the cloud. It can be accessed as a shared file repository in any way that administrators want to permit.
As well as being a CIFS share, Nasuni includes an application that can backup file systems, much like Apple's Time Machine, on an hourly basis, taking snapshots of data that are de-duplicated, then sent to the cloud storage vendor's repository.
In turn, data can be restored by file, folder or in its entirety should disaster (or thieves) strike. The downside is that snapshots currently aren't deleted. We uploaded a snapshot containing an ISO image at the beginning of our tests, and then deleted the ISO, but the snapshot with the ISO in it is still alive. This increases storage costs.
Nasuni can be used on networks with an Active Directory infrastructure, or in a standalone way. There is no API, no WebDav, no Ruby access, and there doesn't need to be, if your goal is an intelligent Internet hard drive.
Data sent from Nasuni's cache to cloud storage is encrypted using OpenPGP with AES-256 strength encryption keys. Not only is data encrypted, but it's compressed as well, before being uploaded to the cloud.
Nasuni asks for a hard drive with a minimum 132GB of free space. Caching increases speed, but made performance testing impossible, as the locus of the data isn't really under our control. It could be on the local storage media, or it might be in the cloud. You may not know or care, except that Nasuni is no faster than the cloud connectivity that's used.
And there's the rub, or benefit: Nasuni costs $300 per month (or less depending on contract term) on top of the cloud storage provider's storage charge. What Nasuni buries into its cost are the cloud storage vendor's transport costs and access charges (relating to GET, POST and so on). Nasuni eats those charges, passing only the storage charge for the data.
The principle advantage to Nasuni storage interface is its simplicity for network file system expansion, where the cloud storage vendor's resources become extensions of the storage network infrastructure. Nasuni makes branch rollouts specifically simple.