IBM General Parallel File System for AIX: Data Management API Guide

DMAPI configuration attributes

The XDSM standard defines a set of configuration attributes, to be exported by each DMAPI implementation. These attributes specify which optional features are supported and give bounds on various resources.

The Data Management (DM) application can query the attribute values using the function dm_get_config. It can also query which events are supported, using the function dm_get_config_events.

The functions dm_get_config and dm_get_config_events receive a file handle (via arguments hanp and hlen). In GPFS, both functions ignore the handle, as the configuration is not dependent on the specific file or file system. This enables the DM application to query the configuration during initialization, when file handles may not yet be available.

Following are the attribute values that are used in GPFS:

Note:

To guarantee that the most current values are being used, the DM application should always query the configuration at runtime by using dm_get_config.

Note:

DM_CONFIG_TOTAL_ATTRIBUTE_SPACE is per file. The entire space is available for opaque attributes. Non-opaque attributes (event list and managed regions) use separate space.