I've built a fairly complete prototype of a block-level virtual disk backed by commodity cloud storage. It provides robust, efficient, zero-maintenance offsite storage ie. it delivers data security.

It works by implementing a massive virtual disk volume (up to 256 Terabytes) formatted with the platform filesystem-of-choice - NTFS/Windows only at this stage.

Block updates are encrypted and compressed on the fly then marshalled and snapshotted before exporting to Amazon S3 (but could be any cloud storage provider).

From the users perspective, they've just added a massive internal hard disk accessible via the standard fileystem access API's and tools. One way of thinking about it is as a cloud-backed-TrueCrypt but with full-volume versioning, thin provisioning and compression added.

Its primary benefits are:

* data security (offsite vs local, cloud storage robustness vs hard disk robustness)

* the ability to map and manage storage capacity many orders of magnitude larger than the local storage capacity of the installation platform ie. 100's of Terabytes of storage available on a tablet.

* it offers a transparent cloud storage gateway - users can leverage of cloud storage via the familiar storage disk model

As opposed to the folder/file representation implemented by the the webdav/fuse offerings, the block-based model retains all of the native filesystem attributes associated with the users files are retained (permissions, encryption, compression) as well as other filesystem metadata (journalling, quotas etc).

Bandwidth and storage overheads are surprisingly low: An empty 256 terabyte NTFS volume still requires a 600mb filesystem metadata overhead, yet that formatted volume can be represented using just 150kb of bandwidth/cloud storage initially while subsequent snapshots to the same volume only incur ~40kb each.

So it can readily and efficently perform regular fine-grained snapshots on user's data, consuming bandwidth and storage in the same ballpark as file-based technologies.

So that's what it does - here's where I am at the moment:

When I first started on it (quite some time back), my initial thoughts were to release it as a pro-sumer product or as a freemium service.

What I have come to realise is that even though tools like DropBox and ZumoDrive are not focused primarily on data security (ie. they deliver sharing and collaboration), the level of mindshare these services enjoy makes marketing any sort of cloud storage offering an uphill task, especially for a startup.

So I have had cause to stop and re-evaluate whether I should push on or drop it.

Consequently, I'm after feedback:

Is this approach/technology/product promising or a dog?

Are the benefits of full-fidelity data compelling enough to differentiate it?

Is it just a solution looking for a problem?