A friend challenged the notion of using Amazon’s EC2 web service to host a startup’s web-site or service because EC2 would be a single-point-of-failure; and he was right! EC2 by itself is not a good hosting option because, if it fails, you have no alternate host. Having said that, high-availability hosting isn’t EC2’s target market low-cost computing resource is.

But we need alternate hosting because it gives us high-availability systems. In general we need diversity measures to negate the failures in real-world systems. EC2 provides a vast pool of low-cost computing resources but it’s ultimately a single-sourced resource.

Ideally we’d use EC2 with another computing provider. The good news is that other providers exist like Mosso, GoGrid, Microsoft and Rackspace so we can get diverse platforms. Now we need a platform to tie our diverse resources together; specifically we need load balancing, auto-scaling, monitoring and management. RightScale produce a suitable product as do WeoCeo.

We can build high-availability systems based on cloud resources, the key is to understand if you want low-cost resources, high-availability or both. Before you embark on building a cloud computing service ask yourself these questions:

Do I want high-availability?
How much am I prepared to pay?
Can I structure my computing tasks to operate in the cloud?
What happens if my system fails?