In our continuing series of groundbreaking tests of cloud computing services, we take a look at what enterprises can expect if they decide to entrust data to a cloud storage provider.

We found that cloud storage lives up to its advance billing in two key areas: cloud storage can be fast and the pay-as-you-go model can be a real cost saver. We also found that security could be an issue for enterprise shops, and the formulas for trying to predict overall costs can be complex.

The services that we tested were Amazon S3, Rackspace's CloudFiles, Egnyte's On Demand File Server, Nasuni Cloud Storage, and Nirvanix's Storage Delivery Network.

Amazon, Rackspace and Nirvanix represent the containerized/object-oriented model. Egnyte embodies the file/folder metaphor, while Nasuni offers a different twist – it's a front-end that simplifies cloud storage for enterprise customers and connects to other cloud storage vendors on the back end.

To test cloud-based storage, we accessed the cloud vendor's site through their supplied APIs, where applicable. We moved data either from virtual machines in our cabinet at n|Frame in Indianapolis at 100Mbps, or from our lab connected via standard Comcast broadband.

We pounded each site with a variety of file sizes ranging from 500KB to 1GB. We also tested in two periods, daytime and nighttime, to see if Internet congestion played a role in cloud storage performance.

Overall, performance was strong, although it was also somewhat random and unpredictable. Generally speaking we did get faster uploads and downloads at night, when Internet congestion is lower. And we found that download speeds were considerably slower than upload speeds for all the vendors tested.

Rackspace delivered the best overall performance, with an average speed 2.57Mbps for uploads and roughly 650Kbps for downloads. But all of the vendors delivered impressive performance.

Nirvanix delivered an average upload speed of 1.3Mbps and Egnyte topped 1Mbps. Amazon had the lowest average upload speed at 835Kbps, but also the highest download speed at 773Kbps, giving it the best balance between upload and download speeds.

Security concerns

Those desiring comfortable high security may be disappointed. While all of the vendors we tested provided link encryption, data encryption was glossed over by the container providers. We wanted to see port scrambling, and IP address access control lists, but these were missing across the board. Admittance control would, for some thinkers, break the cloud model by creating an extranet relationship between a subscriber and the cloud storage area, but we'd feel happier if there were greater admittance control by IP address. At press time, Amazon announced such IP address admittance control, along with HTTP_Referrer control (URL-based admittance), but we were unable to examine it at deadline.

Henderson is principal researcher and Allen is a researcher for ExtremeLabs in Indianapolis. They can be reached at thenderson@extremelabs.com.