John Sequiera ponders the question: "Why on-demand appliances?" He gets virtualization, but the ‘resource pool’ approach of something like Amazon’s EC2 does require a shift in thinking and comfort level with IT as a utility. I think John’s a-ha here is more about the usefulness of virtual appliances, whether they’re in the cloud or in your ESX Server at the data center. I personally see the most need for on-demand computing around capacity management (unexpected DOS attacks or planned seasonal surges) and capital management (why buy when you can lease?).

Link: John Sequeira’s Weblog.

Why is this cool? Well, consider the difference between your typical
startup and a mature web enterprise: to really run a web hosted
application according to best practices, you should have


  • staging setup
  • production setup,
  • hot standby, DR plan
  • version control repository/bug tracker
  • integrated authentication
  • distributed file system
  • load balancer
  • firewall/intrusion detection
  • etc.

And no one does initially because it takes a lot of time, money and
expertise to put all these pieces in place. But what if you could have
it all initially and it didn’t cost an arm and a leg? The idea of a
vendor (like, say Novell or RH) pre-provisioning all the machines
required to pull the above off, and offering them via the Amazon EC2
Control Panel is quite compelling. Imagine the options:


  • Statefull Firewall with mod_security? Check. 
  • Dedicated Image Server pre-configured with optional Akamai CDN support?  Check. 
  • Web analytics reporting server? Check
  • Offline bi/olap database with real-time replication? You get the idea.

Each check on that control panel is the equivalent of days or weeks of work on your hand-rolled data center.