The OpenStack advantageRackspace was one of the main forces behind OpenStack, and the company continues to make the flexibility of the open source cloud stack one of its big selling points. Your enterprise won't be locked into the Rackspace cloud because you can always set up OpenStack in your own data center -- if and when you want to leave Rackspace behind. This flexibility is crucial for many businesses because rewriting code can be quite a pain, especially if it's older code that someone wrote long ago before quitting.
Rackspace brags that it's not just offering you a separate fork of OpenStack, but the actual code running on its cloud machines. "The software is not a separate distribution of OpenStack, so you don't have to worry about a branching dead end," promises the Rackspace website. This is quite an offer and one that's designed to prey on any enterprise manager's worst fears of vendor lock-in.
Rackspace also pushes hybrid architectures that make it possible for you to link up your private cloud with the Rackspace cloud for moments when you need more servers. One customer, for instance, says it turns on servers in the public cloud whenever it runs major ad campaigns. When the traffic surge is over, the website retreats to the private cloud. Running the same OpenStack layer in your data center makes it simpler to do this.
Rackspace is taking a different approach to storing data. While Amazon, Google, HP, and a few others are building elaborate NoSQL abstraction layers that promise elastic scalability, Rackspace is sticking with MySQL, the decades-old, tried-and-true solution to storing information.
You can choose between disk storage and faster SSD when you create a block of storage that can be mounted on your virtual machine.