This may need to happen if you remove/re-add NPIV mapping, if SAN topology changes, or if you have removed maps, ports, cables, or entire LUNs.
1. Change the configuration on the array to remove the extra ports, etc.
2. Physically remove any fibre cables if needed.
3. IPL the server.
4. Run the STRSST command., then Press ENTER
5. Option 1, Start a service tool, then Press ENTER
6. Option 4, Display/Alter/Dump, then Press ENTER
7. Option 1, Display/Alter storage, then Press ENTER
8. Option 2, Licensed Internal Code (LIC) data, then Press ENTER
9. Option 14, Advanced analysis (scroll down to see this option), then Press ENTER
a. Scroll down and type 1 by MULTIPATHRESETTER, then press ENTER
b. Options, -RESETMP -ALL -CONFIRM, then press ENTER
DISPLAY/ALTER/DUMP Running macro: MULTIPATHRESETTER -CONFIRM -ALL Reset the paths for Multiple Connections ******************************************************************** ***CONFIRM RESET MULTIPATH UNIT PATHSTO NUMBER CURRENTLY ENLISTED*** ******************************************************************** This service function should be run only under the direction of the IBM Hardware Service Support. You have selected to reset the number of paths on a multipath unit to equal the number of paths that have currently enlisted. Attempting to reset path for resource name: DMP004 Attempting to reset path for resource name: DMP075 ... *** Your request completed successfully *** The number of paths connected to your multipath unit have been reset to match the number of paths that are currently enlisted.
REF: https://www.ibm.com/support/pages/reducing-or-removing-paths-multipath-lun
REF: https://www.ibm.com/support/pages/san-disks-missing-paths