Veritas™ File System 5.0.1 Administrator's Guide

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.

If space cannot be allocated on any volume in any of the placement classes

specified, file creation fails with an ENOSPC error, even if adequate space is available

elsewhere in the file system's volume set. This situation can be circumvented by

specifying a Flags attribute with a value of "any" in the <ON> clause. If <ON

Flags="any"> is specified in a CREATE statement, VxFS first attempts to allocate

Dynamic Storage Tiering

File placement policy rules

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