Migrating to DMP from IBM Multipath IO (MPIO) or MPIO path control module (PCM)

This procedure describes how to migrate to DMP from IBM Multipath IO (MPIO) or an MPIO path control module (PCM). The procedure includes removing the devices from MPIO control and enabling DMP on the devices.

If an MPIO PCM is installed, you need to remove the PCM before you install the ODM packages from the vendor.

Plan for system downtime for the following procedure.

The migration steps involve system downtime on a host due to the following:

To take the devices out of MPIO control and enable DMP

  1. Obtain the corresponding MPIO-suppression Object Data Manager (ODM) fileset for the array from the array vendor.

    If the MPIO suppression ODM fileset is not available, use the vxmpio utility to remove the device from MPIO.

  2. Stop the applications that use the MPIO devices.
  3. Unmount the file systems on the MPIO devices.
  4. Vary off the LVM volume groups.
    # varyoffvg vgroupname
  5. If an MPIO PCM is present, remove all VxVM devices that the PCM controls.
    # vxdisk rm dmpnodename
  6. If the MPIO PCM does not control the rootvg devices, then uninstall the PCM.

    If a PCM controls the rootvg devices, then you must obtain the script from the PCM vendor to uninstall the PCM. For example, if the Subsystem Device Driver Path Control Module (SDDPCM) controls the devices, then contact IBM to obtain the script to remove SDDPCM.

  7. Install the MPIO-suppression ODM fileset that you obtained from the array vendor in step 1. Refer to the array vendor documentation for the installation procedure.

    Some array vendors do not distribute ODM Pre-defines for their arrays for AIX. In this case, you can use the devices as hdisk devices, as long as MPIO does not claim these LUNs.

  8. Turn on the DMP support for the LVM volume groups.
    # vxdmpadm settune dmp_native_support=on

    The above command also enables DMP support for LVM root.

  9. Reboot the system.
  10. After the reboot, DMP controls the devices. Any LVM volume groups on MPIO devices are migrated onto DMP devices.
  11. Mount the file systems.
  12. Restart the applications.