Constraints

This catalog aggregates constraints related to the management of VMs and servers on hosting platforms. Previous chapters present key elements that may be impacted by a reconfiguration : VM state and placement, server state, resource allocation. The present chapter enumerates numerous constraints that are of a practical interest for applications and datacenter administrators to express dependability or management requirements such as performance, availability or security. Such constraints may then be implemented in different VM managers to provide an initial deployment or a reconfiguration process that is consistent with regards to the expressed constraints.

Each section of this chapter details a specific constraint. First, a definition is provided to specify the guarantees provided by the constraint. A classification allows to categorize the constraint depending on the element it manipulates, the primary concern it addresses or the typical users. Several use cases illustrate then the practical interest of the constraint and examples depicts its impact on a reconfiguration process. Finally, references to closely related constraints are provided.

Several notations are used within this chapter to write the constraints signature or sample configuration. Chapter  "Notations" details these notations.

The current catalog is composed of 21 constraints.