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File placement policy grammar

VxFS allocates and relocates files within a multi-volume file system based on properties expressed in the file system metadata that describes the files. Placement decisions may be based on file name, directory of residence, time of last access, access frequency, file size, and ownership. An individual file system's criteria for allocating and relocating files are expressed in the file system's file placement policy.

A VxFS file placement policy is an internal structure that defines the desired placement of sets of files on the volumes of a VxFS multi-volume file system. A file placement policy specifies the placement classes of volumes on which files should be created and where and under what conditions the files should be deleted or relocated to volumes in alternate placement classes. You can create file placement policy documents, which are XML text files, using either an XML or text editor, or a VxFS graphical interface wizard.

The following output shows the overall structure of a placement policy:

<?xml version="1.0"?>

<!DOCTYPE FILE_PLACEMENT_POLICY SYSTEM

"/opt/VRTSfspro/config/placement_policy.dtd">

<FILE_PLACEMENT_POLICY Version="5.0">

<RULE Name="rule_name">

<SELECT>...selection criteria...</SELECT>

<SELECT>...repeated as necessary...</SELECT>

<CREATE><ON>...creation locations...</ON></CREATE>

<DELETE>

<FROM>...source placement classes...</FROM>

<WHEN>...deletion criteria...</WHEN>

</DELETE>

<DELETE>...repeated as necessary...</DELETE>

<RELOCATE>

<FROM>...source placement classes...</FROM>

<TO>...destination placement classes...</TO>

<WHEN>...relocation criteria...</WHEN>

</RELOCATE>

<RELOCATE>...repeated as necessary...</RELOCATE>

</RULE>

<RULE>...repeated as necessary...</RULE>

</FILE_PLACEMENT_POLICY>