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| Specifying allocation constraints for vxassist operations with the use clause and the require clause | ||
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| Specifying allocation constraints for vxassist operations with the use clause and the require clause | ||
|---|---|---|
| Prev | Customizing allocation behavior | Next |
The vxassist command accepts a variety of storage specifications for allocations. The require constraint and the use constraint are methods to specify detailed storage specifications for allocations. These constraints enable you to select disks from an intersection set or a union set of intended properties. You can specify the set of disks for allocations with more precision than the existing methods alloc and logdisk clauses. The use and require constraints can apply to data, log, or both data and log.
The constraints can be one of the following types:
The require constraints
All of the specifications in the constraint must be satisfied, or the allocation fails. A require constraint behaves as an intersection set. For example, allocate disks from a particular array vendor AND with a particular array type.
The use constraints
At least one of the specifications in the constraint must be satisfied, or the allocation fails. A use constraint behaves as a union set. For example, allocate disks from any of the specified enclosures: enclrA or enclrB.
For disk group version of 180 or above, the use and require type of constraints are persistent for the volume by default. The default preservation of these clauses enables further allocation operations like grow, without breaking the specified intents.
You can specify multiple storage specifications, separated by commas, in a use or require clause on the vxassist command line. You can also specify multiple use or require clauses on the vxassistcommand line.
See Interaction of multiple require and use constraints.
Use the vxassist intent management operations (setrule, changerule, clearrule, listrule) to manage persistent require and use constraints.
See Management of the use and require type of persistent attributes .