IOM12B missing after a scheduled power maintenance

Applies to

• DS460C
• IOM12B

Issue

During a power maintenance exercise on site, the system was gracefully shut down. The entire rack was powered down by switching off the feeds to the rack PDUs. Upon powering the systems back on, a health check revealed that the shelf had only a single path to both controllers. 

• The bottom IOM module on DS460C had no LEDs on.
• After flipping the PSU switch, the LEDs on the IOM module were restored.
• After 2-3 minutes, the cluster performs a takeover

 ::> system health alert show
               Node: node01
           Resource: Shelf 1.10
           Severity: Major
    Indication Time: Thu Aug 08 15:47:22 2024
           Suppress: false
        Acknowledge: false
     Probable Cause: Controller node01 has only a single-path
                     configuration to disk shelf 1.10. This might occur
                     when the controller does not have dual-path
                     configuration to stack 1, a SAS HBA port on the
                     controller connected to the disk shelf is disabled, or
                     shelf-to-shelf cabling is incorrect.
    Possible Effect: Access to disk shelf 1.10 via controller node01
                     might be lost with a failure of controller 3a port, a
                     single shelf-to-shelf cable or a single disk shelf IOM.
Corrective Actions: 1. Consult the guide applicable to your IOM12B disk shelf to review cabling rules and complete the SAS cabling worksheet for your system.
                     2. Connect controller node01 to the first and last disk shelf of stack 1 using active SAS HBA ports.
                     3. Verify that controller node01 is cabled to IOM A at one end and IOM B at another end of stack 1.
                     4. If disk shelf 1.10 is located between two disk shelves within stack 1, verify that IOM A and IOM B are properly cabled to their 
                         independent domains.
                     5. Contact technical support if the alert persists.

• Sysconfig -a shows blank for IOM12B module B 

Shelf 10: DS460-12 Firmware rev. IOM12B A: 0141 B: ----