Elasticity (computing): Difference between revisions

Revision as of 13:54, 22 August 2016

Revision as of 16:18, 24 August 2016

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==Purpose==

Elasticity aims at matching the amount of resource allocated to a service with the amount of resource it actually requires, avoiding over- or under-provisioning. '''Over-provisioning''', i.e., allocating more resources than required, should be avoided as the service provider often has to pay for the resources that are allocated to the service. For example, at the time of this writing,an [[Amazon EC2]] chargesM4 extra-large instance costs [[US$]]0.480239/hour for an "extra large" virtual machine. If a service is allocated two virtual machines, instead of one required, the service provider wastes $4,205 every year. Hence, the service provider's [[expenses]] are higher than optimal and the [[Profit (accounting)|profit]] is reduced.

'''Under-provisioning''', i.e., allocating fewer resources than required, must be avoided, otherwise the service cannot serve its users with a good service. In the above example, under-provisioning the website may make it seem slow or unreachable. Web users eventually give up on accessing it, thus, the service provider loses customers. On the long term, the provider's [[income]] will decrease, which also reduces the profit.