PowerEdge: What is a CTL137 Event and How to Troubleshoot it

Summary: The CTL137 event is new to iDRAC code 4.xx.xx.xx. The CTL137 event exist to notify the end user that the iDRAC lost communication with an endpoint device within the system.

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Symptoms

What is a CTL137 Event?
The CTL137 event is new to iDRAC code 4.xx.xx.xx. The CTL137 event exist to notify the end user that the iDRAC lost communication with an endpoint device within the system.

Example:
"The storage controller PCIe SSD in Slot X in Bay X is unable to communicate to the BMC because either the storage controller or BMC is not responding to the commands either because of an internal error or the bus is in an error state."

Cause

What Triggers a CTL137 Event.
The iDRAC continuously polls the end-point devices (NVMe drives, PERC, and so forth) over the i2C channel within the system for various reasons (Health Status changes, Temperature, and so forth). If an endpoint device fails to respond to 10 consecutive i2C polls, then the iDRAC logs a CTL137 event. To notify the end user that the iDRAC lost communication with the endpoint device.

Will the iDRAC notify you when communication is restored?
If i2C communication to the endpoint device is restored after a CTL137 is generated. Observing a CTL138 event notifies the user that communication has been restored to the endpoint device.

Example:
"CTL138 The communication between storage controller PCIe SSD in Slot X in Bay X and the BMC is restored"

Why does an iDRAC reset temporarily resolve the issue.
By performing an iDRAC reset, you are forcing the system to re-inventory the attached endpoint devices. Also in the process the iDRAC command failed counter for each endpoint device is reset to 0 for each endpoint device. Once the endpoint device fails to respond to 10 consecutive i2C polls then the iDRAC logs a CTL137 event against that endpoint device. 

Why am I seeing a CTL137 event and the drive is still online within the Operating SystemOS.
In some situations you may see that the drive is still online within the OS yet, you are seeing a CTL137 event. This is because the i2C communication to the drives does not go through the data cables. The iDRAC sends all SMBus communication using a single SIG cable that goes from the planar to the backplane. Your issue might be with these components.

Resolution

What to look for when you see a CTL137 event.

  1. Look for the obvious reasons as to why the drive may have failed to reply to an i2C poll from the iDRAC.
    1. Did a drive fail?
    2. PCIe Link Training Failure
    3. PCI Down Train Errors
  2. Verify that all the components within the system NVMe Drive, backplane, iDRAC are on the latest code. 
  3. After steps 1 and 2 have been performed and if still seeing repeated CTL137 events followed by CTL138 events. Then you are likely seeing an intermittent Signal issue between the iDRAC and the endpoint device.
    1. Attempt to reseat the drive and or backplane cables to the planer.

Affected Products

OEMR XL R570, OEMR XL R670, OEMR R450, OEMR R540, OEMR R550, OEMR R640, OEMR R6415, OEMR R650, OEMR R650xs, OEMR R6515, OEMR R6525, OEMR R660, OEMR R660xs, OEMR R6615, OEMR R6625, OEMR R740, OEMR R740xd, OEMR R740xd2, OEMR R7415, OEMR R7425 , OEMR R750, OEMR R750xa, OEMR R750xs, OEMR R7515, OEMR R7525, OEMR R760, OEMR R760xa, OEMR R760XD2, OEMR R760xs, OEMR R7615, OEMR R7625, OEMR R840, OEMR R860, OEMR R940, OEMR R940xa, OEMR R960, OEMR XL R6715, OEMR XL R6725, PowerEdge R440, PowerEdge R450, PowerEdge R470, PowerEdge R540, PowerEdge R550, PowerEdge R570, PowerEdge R640, PowerEdge R6415, PowerEdge R650, PowerEdge R650xs, PowerEdge R6515, PowerEdge R6525, PowerEdge R660, PowerEdge R660xs, PowerEdge R6615, PowerEdge R6625, PowerEdge R670, PowerEdge R6715, PowerEdge R6725, PowerEdge R740, PowerEdge R740XD, PowerEdge R740XD2, PowerEdge R7415, PowerEdge R7425, PowerEdge R750, PowerEdge R750XA, PowerEdge R750xs, PowerEdge R7515, PowerEdge R7525, PowerEdge R760, PowerEdge R760XA, PowerEdge R760xd2, PowerEdge R760xs, PowerEdge R7615, PowerEdge R7625, PowerEdge R770, PowerEdge R7715, PowerEdge R7725, PowerEdge R7725xd, PowerEdge R840, PowerEdge R860, PowerEdge R940, PowerEdge R940xa, PowerEdge R960 ...
Article Properties
Article Number: 000182797
Article Type: Solution
Last Modified: 09 July 2025
Version:  3
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