Rules

Rules specify the criteria for allocating storage, the criteria for laying out VxVM objects on storage, and the relationship between these objects. Rules can be classified as storage selection rules that define how to choose storage, or as storage layout rules that define how storage is to be used.

You can optionally precede any rule with the keyword desired. This modifier means that ISP tries to honor this rule, but it can discard it if the rule would cause the allocation to fail. An optional integer after the desired keyword specifies the preference order value for the rule. If specified, this number must be greater than or equal to 1. If no preference order value is specified for a rule, a value of 1 is assumed. Rules with low preference order values are preferred to be retained over rules with higher values. Rules with the same preference order are discarded together.

In the following example, the stripe rule can be dropped if there is insufficient storage to fulfill the storage allocation request: