VERITAS Storage Foundation 4.1 Intelligent Storage Provisioning Administrator's Guide

Rules
120 VERITAS Storage Foundation ISP Administrator’s Guide
requires Reliable
provides Snapshot
rules {
...
}
};
This template picks up any templates that provide the Reliable capability, and merges their
rules with its own rules. If the template were also required to provide the Reliable
capability, the inherits keyword should be used as shown here:
volume_template MyReliableSnapshot {
inherits Reliable
provides Snapshot
rules {
...
}
};
This template provides the Snapshot capability through its own rules, and also provides the
Reliable capability by using rules from other templates.
Note By allowing ISP to choose any template that provides the required capability, the
requires keyword gives ISP more flexibility when allocating storage. This behavior is
known as dynamic inheritance.
When choosing a template with a required capability, ISP gives preference to templates that
provide only that capability. This behavior avoids giving unrelated capabilities to a volume.
When searching for a template with a required capability, ISP chooses only those templates
that inherit or provide that capability.
When searching for a template with a required capability, ISP recursively chooses templates
that provide all the required capabilities.
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,