Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

A placement policy rule's action statements apply to all files designated by any

of the rule's SELECT statements. If an existing file is not designated by a SELECT

statement in any rule of a file system's active placement policy, then SmartTier

does not relocate or delete the file. If an application creates a file that is not

designated by a SELECT statement in a rule of the file system's active policy, then

VxFS places the file according to its own internal algorithms. If this behavior is

inappropriate, the last rule in the policy document on which the file system's

active placement policy is based should specify <PATTERN>*</PATTERN> as the

only selection criterion in its SELECT statement, and a CREATE statement naming

the desired placement class for files not selected by other rules.

CREATE statement

A CREATE statement in a file placement policy rule specifies one or more placement

classes of volumes on which VxFS should allocate space for new files to which the

rule applies at the time the files are created. You can specify only placement

classes, not individual volume names, in a CREATE statement.

A file placement policy rule may contain at most one CREATE statement. If a rule

does not contain a CREATE statement, VxFS places files designated by the rule's

SELECT statements according to its internal algorithms. However, rules without

CREATE statements can be used to relocate or delete existing files that the rules'

SELECT statements designate.

The following XML snippet illustrates the general form of the CREATE statement:

<CLASS> placement_class_name </CLASS>

<BALANCE_SIZE Units="units_specifier"> chunk_size

</BALANCE_SIZE>

</DESTINATION>

<DESTINATION> additional_placement_class_specifications

</DESTINATION>

</ON>

</CREATE>

A CREATE statement includes a single <ON> clause, in which one or more

<DESTINATION> XML elements specify placement classes for initial file allocation

in order of decreasing preference. VxFS allocates space for new files to which a

rule applies on a volume in the first class specified, if available space permits. If

space cannot be allocated on any volume in the first class, VxFS allocates space

on a volume in the second class specified if available space permits, and so forth.

351Administering SmartTier

File placement policy rules