Enabling DMAPI for a file system

DMAPI can be enabled for a file system when the file system is created, using the -z yes option on the mmcrfs command. The default is -z no. The setting can be changed when the file system is not mounted anywhere, using the -z yes | no option on the mmchfs command. The setting is persistent.

The current setting can be queried using the -z option on the mmlsfs command.

While DMAPI is disabled for a given file system, no events are generated by file operations of that file system. Any DMAPI function calls referencing that file system fail with an EPERM error.

When mmchfs -z no is used to disable DMAPI, existing event lists, extended attributes, and managed regions in the given file system remain defined, but will be ignored until DMAPI is re-enabled. The command mmchfs -z no should be used with caution, since punched holes, if any, are no longer protected by managed regions.

For more information about GPFS commands, see Command reference.