A storage policy includes one or several rule sets that describe requirements for virtual machine storage resources.
When you define a storage policy for your virtual machines, you can add one or multiple rule sets, also called subprofiles. A single rule set contains one or several rules. Each rule describes a specific quality or quantity that needs to be provided by a storage resource. Each rule can either be an underlying storage capability or a user-defined storage tag. One rule set can include rules from only a single storage provider.
To create a policy, one rule set is required, while additional rule sets are optional. Multiple rule sets allow a single policy to define alternative selection parameters, often from several storage providers.
The relationship between all rule sets within a policy is defined by the Boolean operator OR, while the relationship between all rules within a single rule set is defined by AND. Meeting all the rules of any one rule set is sufficient to satisfy the entire policy. Each rule set represents an equally acceptable set of constraints.