DS8000 Service Documentation Version 7.5

MAP2230 Overcurrent on DDM power boundary for both PPSs

Both PPSs have reported an overcurrent condition for one or more of the 5/12 VDC device power boundaries in the affected rack. The affected storage enclosures (front or back) will not be powered and access to customer data could be lost.

About this task

Each DDM within a storage enclosure contains a self-healing fuse. In addition, the FCIC logic card has built in current limiting to provide overcurrent protection. The following is a list of the components in the voltage distribution path, all of which could introduce a short.
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MAP2230 Section-1

Procedure

  1. Use the FRU list to determine the location of the 5/12V DDM modules reporting the failure. The FRU list should contain the 5/12V DDM module in both primary power supplies (PPS).
    Note: If the optional 5/12V DDM modules are installed, they also supply power to the same bus bars, so will see and may report the same overcurrent.
  2. Display serviceable events that need repair. Is there any other serviceable event related to the power system for the DDMs?
    • Yes, exit this MAP and attempt to repair the other serviceable event first. If that repair does not correct this problem also, return here and go to the next step.
    • No, go to the next step.
  3. Are the same LEDs on the 5/12V DDM modules on both PPSs lit amber?
    • Yes, go to the next step.
    • No, exit this MAP and contact your next level of support.
  4. Determine which output section of the 5/12V DDM module is reporting the error. Observe the amber LEDs.
    • The upper output section of the 5/12V DDM module (J1-A connector and nearby LEDs) supplies power for the front storage enclosures.
    • The lower output section of the 5/12V DDM power module (J2-A connector and nearby LEDs) supplies power for the rear storage enclosures.
    Note: If the optional 5/12V DDM power modules are installed (to the right of the base 5/12V DDM module), they also should have the same LED indication. The optional modules feed the same power buses.
  5. Determine if the 5/12V DDM module in PPS-1 is causing the failure.
    1. Disconnect the cable from PPS-1 5/12V DDM module next to the LED lit amber. If the optional 5/12V DDM module is installed, disconnect the cable next to the LED lit amber.
    2. Reset the 5/12V DDM modules by setting the enable/disable switch below the amber LED to disable (down) and then enable (up). Also do this on the optional module, if installed.
    Is the LED now lit green?
    • Yes, the module in PPS-1 is not failing. Reconnect the cables and then go to the next step.
    • No, the 5/12V DDM module with the LED lit amber is failing and needs to be replaced. Return to the repair screen that sent you here to replace the FRU.
  6. Determine if the 5/12V DDM module in PPS-2 is causing the failure.
    1. Disconnect the cable from PPS-1 5/12V DDM module next to the LED lit amber. If the optional 5/12V DDM module is installed, disconnect the cable next to the LED lit amber.
    2. Reset the 5/12V DDM modules by setting the enable/disable switch below the amber LED to disable (down) and then enable (up). Also do this on the optional module, if installed.
    Is the LED now lit green?
    • Yes, the module PPS-2 is not failing. Reconnect the cable(s) and then go to step 8.
    • No, the 5/12V DDM module with the LED lit amber is failing and needs to be replaced. Go to step 7.
  7. PPS-1 should be able to supply the needed power to the storage enclosures that do not currently have power.
    1. Reset the PPS-1 5/12V DDM modules by setting the enable/disable switch below the amber LED to disable (down) and then enable (up). Also do this on the optional module, if installed. The LEDs on the module should now be lit green.
    2. Return to the repair screen that sent you here to replace the FRU.
  8. The overcurrent is not caused by a failure in either PPS. The failure is caused by one of the following:
    • Cable between the DDM power module(s) and the secondary device distribution bus bar.
    • Secondary device distribution bus bar mounted at the back center of the machine.
    • Primary device distribution bus bar which runs vertically between the device enclosures.
    • Bus bar jumpers between the primary and secondary device distribution bus bar.
    • Cable between each storage enclosure assembly and the primary device distribution bus bar.
    • Storage enclosure assembly.
    • FCIC logic cards (not likely as this has built in overcurrent protection).
    • DDMs (not likely as this has built in overcurrent protection).