Abnormal Fan Rotation Speed due to Backplane Failure of the E6000

Publication Date:  2012-07-17 Views:  164 Downloads:  0
Issue Description
At a commercial deployment, the E6000 encounters abnormal fan rotation speed and noise. By checking its rear panel, the indicator of slot 7 is lit red, as shown in figure 1. Besides, the rotation speed of a fan in the leftmost column is found abnormal by choosing System Status > Heat Dissipation Management on the ISM, as shown in figure 2.
Figure 1 Alarming red indicator of slot 7
Figure 2 Abnormal rotation speed of the fan #1-4-7
Alarm Information
Handling Process
Step 1  Swap the fan in slot 7 for the one in another slot for troubleshooting, and the problem persists. Therefore, the problem is irrelevant to the fan module.
Step 2  Remove the alternate SMM 610 on the right of the rear panel for further troubleshooting, and the problem still persists. Switch the preferred MM to the alternate MM that is located on the right by removing the SMM 610 on the left, and the alarm disappears this time. And then, insert the removed MM, and the device is still running properly. Therefore, the disability of managing the fan module by one of the MMs leads to this problem.
Step 3  Repeat step 2 after swapping the two MMs, and the same result is produced as described in step 2. Therefore, hardware of both MMs is fault-free. Now, we can see that the root cause lays in the connection between the left SMM 610 and the E6000 backplane. If possible, check the slot where the left SMM locates on the backplane for bent pins or other obvious physical defects.
Step 4  Use the right SMM 610 as the preferred MM for the moment. To completely correct the problem, replace the E6000 backplane once possible.
Root Cause
Given the fan rotation speed is directly controlled by the SMM 610, this problem may be occurred for the following three reasons:
1. Hardware failure of the fan module.
2. MM failure that results in the abnormal fan module.
3. Bent pins or physical defects of the backplane that result in SMM 610 connection failure