This article explains why sensord may report a "sensord: rrd update error (-1)" on MX Series routers and indicates the action that can be taken to resolve the error, which is observed to be purely cosmetic.

The following error logs are seen pertaining to Linux-based Flexible PIC Concentrators (FPCs) (MPC7/8/9 and so on).

fpc3 daemon.notice sensord: rrd update error (-1)
fpc3 daemon.err sensord: Error updating RRD file: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd: /var/run/sensord.rrd:

sensord is responsible for monitoring sensors and logging sensor details at different timestamps. This log file stays in the hard disk of the FPC. If the FPC power goes off abruptly any time and if this file gets corrupted, sensord complains about this corrupted file.

This error can also be seen on new installations of the FPC if the FPC time is in the future when compared to the system time.

These errors are cosmetic and should not cause any functionality impact.

However, to recover and resolve the errors, perform the following steps:

1. Log in to the router as the root user and go to the FPC Linux shell:

labroot@router-re1> start shell pfe network base-os fpc0
root@-fpc0:~#

2. Now delete the sensord.rrd file.

root@-fpc0:~# rm /var/run/sensord.rrd

3. Restart the sensord process.

root@-fpc0:~# /etc/init.d/sensord restart

An example from a lab device is as follows:

labroot@router-re1> start shell user root
Password:
root@router-re1:/var/home/labroot #
 
root@router-re1:/var/home/labroot # cli
labroot@router-re1> start shell pfe network base-os fpc0
root@-fpc0:~# rm /var/run/sensord.rrd
root@-fpc0:~# ps -aux | grep sensord
root        1005  0.0  0.0  59964  2076 ?        Ss   Apr09   0:05 /usr/sbin/sensord -i60s -l30m -t1m -r/var/run/sensord.rrd -a
root      113456  0.0  0.0   4392   752 pts/0    S+   15:45   0:00 grep sensord
root@-fpc0:~# /etc/init.d/sensord restart
Restarting sensors logging daemon: sensord...
Stopping sensors logging daemon: sensord... stopped /usr/sbin/sensord (pid 1005)
done.
Starting sensors logging daemon: sensord... done.
done.
root@-fpc0:~# ps -aux | grep sensord      
root      113466  0.0  0.0  59964   624 ?        Ss   15:45   0:00 /usr/sbin/sensord -i60s -l30m -t1m -r/var/run/sensord.rrd -a
root      113468  0.0  0.0   4392   748 pts/0    S+   15:45   0:00 grep sensord
root@-fpc0:~# exitrlogin: connection closed

At this point, the error logs will no longer be seen. The FPC remains up during this procedure.

labroot@router-re1> show chassis fpc detail
Slot 0 information:
  State                               Online   
  Total CPU DRAM                 3136 MB
  Total RLDRAM                    771 MB
  Total DDR DRAM                 18432 MB
  Temperature                      57 degrees C / 134 degrees F
  Start time                          2019-04-10 00:01:38 CST
  Uptime                              6 days, 23 hours, 44 minutes, 5 seconds
  Max MPC base power consumption   910 Watts
  Max MIC1 power consumption       155 Watts
  Max MPC total power consumption 1065 Watts
 
labroot@router-re1>