  Infrastructure as a service (IaaS) systems offer on demand virtual
infrastructures so reliably and flexibly that users expect a high service
level. Therefore, even with regards to internal IaaS behaviour, production
clouds only adopt novel ideas that are proven not to hinder established service
levels. To analyse their expected behaviour, new ideas are often evaluated with
simulators in production IaaS system-like scenarios. For instance, new research
could enable collaboration amongst several layers of schedulers or could
consider new optimisation objectives such as energy consumption. Unfortunately,
current cloud simulators are hard to employ and they often have performance
issues when several layers of schedulers interact in them. To target these
issues, a new IaaS simulation framework (called DISSECT-CF) was designed. The
new simulator's foundation has the following goals: easy extensibility, support
energy evaluation of IaaSs and to enable fast evaluation of many scheduling and
IaaS internal behaviour related scenarios. In response to the requirements of
such scenarios, the new simulator introduces concepts such as: a unified model
for resource sharing and a new energy metering framework with hierarchical and
indirect metering options. Then, the comparison of several simulated situations
to real-life IaaS behaviour is used to validate the simulator's functionality.
Finally, a performance comparison is presented between DISSECT-CF and some
currently available simulators.
