While private clouds are pitched as ideal for companies concerned about security and regulatory compliance, Cameron cautions that private clouds force implementers to rethink how they do security. For example, traditional firewalls won't always provide satisfactory security in cloud environments where workloads can be moved around to less-secure portions of the network. So Suncorp is now virtualizing its firewalls.
Keeping Up With Demand
Jeffrey Driscoll, a systems engineer at consultancy Precision IT Group LLC, says the basic building blocks of a private cloud are servers, storage (such as a SAN) and virtualization software. "Then you start building a cluster," he says, and after that cluster is complete, "capacity planning becomes critical."
Capacity planning involves figuring out what happens when you add servers and other resources to the cluster as needed to keep up with business demand. Capacity planning is a major component of the cluster and the cloud's performance. If it's done wrong, you might end up with useless systems or have to shoehorn-in traditional, noncloud systems to keep things running.
Most organizations aren't good at monitoring and keeping ahead of capacity. To be able to satisfy user demands, you always need to have some extra capacity on the data center floor, which results in a certain amount of hardware sitting around in idle mode. Keeping a history of capacity usage in your enterprise can help you be reasonably confident that you have sufficient -- but not too much -- capacity.
One solution is to create a hybrid cloud environment and move requests for capacity to public clouds, such as Amazon.com Inc.'s Elastic Compute Cloud, when capacity isn't available in the private cloud.
Once the cluster is up and running, you can start provisioning virtual servers. The result is a tiered architecture with a server layer, a network layer and a virtualization layer. There is a management tool at each layer. "Now you can start thinking about automation," Driscoll says.
In Perspective: Storm Clouds On the Horizon
Building your own private cloud involves some challenges, including the following:
* Budget. Private clouds can be expensive, so figure out the upper and lower bounds for your return on investment.
* Integration with public clouds. Build your private cloud so you can move to a hybrid model if you need public cloud services. This will involve making sure systems are secure and verifying that you can run your workloads in both places, among other things.