The chassis process (chassisd) could not read back information from the Chassis Management Bus (CMB) about the indicated component (field-replaceable unit, or FRU).
The problem related to this syslog message is described in the following sections:
The CHASSISD_CMB_READBACK_ERROR message is logged when the chassisd process is not able to read information from the component stated in the message.
When there is a read error on the Chassis Management Bus, it logs the action into the syslog. Below are some examples of the message:
CHASSISD_CMB_READBACK_ERROR: Readback error from chassis management bus for FPC 7 ([0xf7, 0xf0] -> 0x0)
CHASSISD_CMB_READBACK_ERROR: CMB readback error reading FPC#1 [0xf1, 0xf0] -> 0x8
CHASSISD_CMB_READBACK_ERROR: CMB readback error reading CB#1 [0xe7, 0xf2] -> 0x0
The cause for such a notification can be due to a hardware state condition.
Use these command outputs to see if any of the system components are reporting errors:
show log messages
show log chassisd
It may also be possible to keep track of the errors being reported in the PFE with this command:
show pfe statistics error
If the message refers to an FPC or FEB, then obtain the logs from the FPC/FEB to see what errors they are recording on the component itself. This can be done with one of the following sets of commands:
start shell pfe network [fpc#/scb#]
> show syslog messages
> show nvram
request pfe execute command "show syslog messages" target [fpc#/scb#]
request pfe execute command "show nvram" target [fpc#/scb#]
Be sure to replace the [fpc#/scb#] entry above with the reference to the system component that is reporting the log message.
Follow these troubleshooting steps to work towards resolution of the issue:
- Check the messages and chassisd outputs to see if any components are reporting errors in association with the CHASSISD_CMB_READBACK_ERROR message.
- Reserve a maintenance window to offline and online the suspected component(s) to force a reset.
- If the issue still remains, reseat the component(s) in their slots.
- See if it is possible to swap the component with an identical unit in the system, or with a spare.