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• Does the application have stringent compliance
requirements?
• What is the impact to your business if the application
is up but unreachable?
These factors tend to be interrelated. High I/O requirements
or the need to run as part of an ecosystem will affect the
cost of running an application in the cloud.
Once you have the right cloud decision matrix for your orga-
nization, you can evaluate individual applications against it.
Some applications will rank as prime candidates; some appli-
cations will clearly not be well-suited to move to the cloud
and will probably never be moved; others may require a
little work to make them cloud ready.
TWO CLASSES OF APPLICATIONS THAT BELONG
IN THE PUBLIC CLOUD
As a rule, very few existing enterprise applications were
engineered to be well-suited to the public cloud. It may be
years before legacy applications evolve to be public cloud
ready—if they ever do. If you move an application that isn't
ready to the public cloud, you'll likely find you're burning
money and not meeting your business needs.
The applications that do belong in the cloud fall into
two categories:
• Highly elastic applications
• New applications where you don't yet understand
the demand
Applications that have a low ecosystem requirement and are
very elastic—have highly variable resource requirements—are
often perfect for the public cloud. They can get all the resources
they need when they need them and release them when they
don't. Hosting a highly elastic application on-premises might
mean having to provision a large amount of expensive infra-
structure to accommodate occasional activity spikes.
