Dynamic Multi-Pathing (DMP) provides Array Policy Modules (APMs) for use with an array. An APM is a dynamically loadable kernel module (or plug-in) that defines array-specific procedures and commands to:
Select an I/O path when multiple paths to a disk within the array are available.
Select the path failover mechanism.
Select the alternate path in the case of a path failure.
Put a path change into effect.
Respond to SCSI reservation or release requests.
DMP supplies default procedures for these functions when an array is registered. An APM may modify some or all of the existing procedures that DMP provides, or that another version of the APM provides.
# vxdmpadm listapm all
The output from this command includes the file name of each module, the supported array type, the APM name, the APM version, and whether the module is currently loaded and in use.
To see detailed information for an individual module, specify the module name as the argument to the command:
# vxdmpadm listapm module_name
# vxdmpadm -a cfgapm module_name [attr1=value1 \ [attr2=value2 ...]]
The optional configuration attributes and their values are specific to the APM for an array. Consult the documentation from the array vendor for details.
By default, DMP uses the most recent APM that is available. Specify the -u option instead of the -a option if you want to force DMP to use an earlier version of the APM. The current version of an APM is replaced only if it is not in use.
# vxdmpadm -r cfgapm module_name
See the vxdmpadm(1M) manual page.