Industrial strength cloud file storage [closed]

Question

I'm looking for an industrial strength cloud file storage system. It will be used by multiple people in a startup.

Our requirements:

• Transparent file system access: files and folders in the file system must be able transparently access (read and write) files in the cloud; files must be synchronized whenever network access is available and buffered otherwise. The system must be usable by non-technical people.
• Access control: we need to control who can access which files, at least on a very coarse basis. e.g., the developers will be able to access the system design documents, only the corporate folks can access recruiting documents, and only management can access certain corporate documents. Dropbox provides this via Sharing folders, but that's not adequate, if I understand it correctly, because there's no authentication of the sharing user. so the cloud service should have a notion of an account (our startup) with multiple users with distinct credentials and rights for each user
• Clients: it must be accessible from Macs and PCs; I would hope that it supports Linux (e.g., Ubuntu) too
• Security: it must provide robust security
• Backup: the cloud service must reliably backup the files
• Versioning: change version history, is a big plus, but not required
• Not free: we're willing to pay for the service

So far, we've reviewed the following, albeit not completely thoroughly:

• Dropbox: has all except 1) Access control, which is provided via Sharing folders, but that's not adequate, if I understand it correctly, because there's no authentication of the sharing user. and 2) Security, as discussed here http://www.economist.com/blogs/babbage/2011/05/internet_security and here http://blog.dropbox.com/?p=821.
• Windows Live Mesh, has all except 1) Clients, only supporting Windows 7 and OS X.
• SpiderOak has all, except 1) Transparent file system access, which is only available for 1 user.
• Amazon Cloud, doesn't offer 1) Transparent file system access
• Rackspace Cloud Drive has all except 1) Access control and 2) Versioning

I'll gladly include any clarifications or additional systems the community provides.

Answer 1

One possibility for you is Wuala (www.wuala.com).

• Transparent fs access: can mount as a volume (disk drive). Can also sync folders.
• Access control, can "share" folders with other Wuala accounts (who must authenticate first)
• Clients (Windows, Mac, Linux - I worked with it on Windows and Ubuntu). There are also clients for mobile devices
• Security: files are encrypted on the client side
• Backup and versioning: has both options, see here http://www.wuala.com/en/learn/features/t/3

Other notes: In general, even with encryption, the speed is good. Have not noticed much difference with Dropbox and JungleDisk. Please do not underestimate importance of encryption with cloud storage, especially for business.

Answer 2

I'd use rsync.net.

While it's not a mountable filesystem, it's trivial to set a local directory and synchronize whenever you have network access.

The biggest plus is that it uses a real standard protocol, so that you're free to use any of lots of tools and not limited by their software.

You can define any number of users and use real filesystem-level access control. If you use the default ssh access method, all communications is encrypted and (preferably) using public-key infrastructure. again, using standards and not whatever they manage to develop.

Backup is available at an extra cost, but if you have a copy in every client, in a sense the 'central' copy is already a backup of your local copy. you have to decide if that's enough or if you want them to keep extra copy.

They don't have a versioning system, but support rdiff-backup, which lets you manage your own using time-tested tools.

Reads like an ad, but i'm not related to them.