1. A method of determining a predicted failure rate in a system comprising multiple components, wherein said system provides one or more computational resources, the method comprising: storing failure rate information about individual components; determining a current configuration of components within the system; identifying from the current configuration dependencies between components within the system; and using the stored failure rate information and the identified current configuration dependencies to generate a predicted overall failure rate for each of said one or more computational resources provided by the system in its current configuration, wherein the overall failure rate for a computational resource represents a combined probability of failure for both the components within the computational resource and the components in devices that are not within the computational resource, but provide support for the computational resource.