This documentation is for an older version of the software. If you are using the current version of Cumulus Linux, this content may not be up to date. The current version of the documentation is available here. If you are redirected to the main page of the user guide, then this page may have been renamed; please search for it there.

Monitoring System Hardware

You monitor system hardware in these ways, using:

  • decode-syseeprom
  • sensors
  • smond
  • Net-SNMP
  • watchdog


  • decode-syseeprom
  • dmidecode
  • lshw
  • sensors
  • smond

Monitoring Hardware Using decode-syseeprom

The decode-syseeprom command enables you to retrieve information about the switch’s EEPROM. If the EEPROM is writable, you can set values on the EEPROM.

For example:

cumulus@switch:~$ decode-syseeprom
TlvInfo Header:
   Id String:    TlvInfo
   Version:      1
   Total Length: 114
TLV Name             Code Len Value
-------------------- ---- --- -----
Product Name         0x21   4 4804
Part Number          0x22  14 R0596-F0009-00
Device Version       0x26   1 2
Serial Number        0x23  19 D1012023918PE000012
Manufacture Date     0x25  19 10/09/2013 20:39:02
Base MAC Address     0x24   6 00:E0:EC:25:7B:D0
MAC Addresses        0x2A   2 53
Vendor Name          0x2D  17 Penguin Computing
Label Revision       0x27   4 4804
Manufacture Country  0x2C   2 CN
CRC-32               0xFE   4 0x96543BC5
(checksum valid)

Command Options

Usage: /usr/cumulus/bin/decode-syseeprom [-a][-r][-s [args]][-t]

Option Description
-h, –help Displays the help message and exits.
-a Prints the base MAC address for switch interfaces.
-r Prints the number of MACs allocated for switch interfaces.
-s Sets the EEPROM content if the EEPROM is writable. args can be supplied in command line in a comma separated list of the form '<field>=<value>, ...'. ',' and '=' are illegal characters in field names and values. Fields that are not specified will default to their current values. If args are supplied in the command line, they will be written without confirmation. If args is empty, the values will be prompted interactively.
-t TARGET Selects the target EEPROM (board, psu2, psu1) for the read or write operation; default is board.
-e, –serial Prints the device serial number.

You can also use the dmidecode command to retrieve hardware configuration information that’s been populated in the BIOS.

You can use apt-get to install the lshw program on the switch, which also retrieves hardware configuration information.

Monitoring Hardware Using sensors

The sensors command provides a method for monitoring the health of your switch hardware, such as power, temperature and fan speeds. This command executes lm-sensors.

For example:

cumulus@switch:~$ sensors
Adapter: i2c-1-mux (chan_id 0)
temp1:        +39.0 C  (high = +75.0 C, hyst = +25.0 C)

Adapter: i2c-1-mux (chan_id 0)
temp1:        +35.5 C  (high = +75.0 C, hyst = +25.0 C)

Adapter: i2c-1-mux (chan_id 1)
in1:         +11.87 V
in2:         +11.98 V
power1:       12.98 W
curr1:        +1.09 A

Adapter: i2c-1-mux (chan_id 2)
fan1:        13320 RPM  (div = 1)
fan2:        13560 RPM

Output from the sensors command varies depending upon the switch hardware you use, as each platform ships with a different type and number of sensors.

Command Options

Usage: sensors [OPTION]... [CHIP]...

Option Description
-c, –config-file Specify a config file; use - after -c to read the config file from stdin; by default, sensors references the configuration file in /etc/sensors.d/.
-s, –set Executes set statements in the config file (root only); sensors -s is run once at boot time and applies all the settings to the boot drivers.
-f, –fahrenheit Show temperatures in degrees Fahrenheit.
-A, –no-adapter Do not show the adapter for each chip.
--bus-list Generate bus statements for sensors.conf.

If [CHIP] is not specified in the command, all chip info will be printed. Example chip names include:

  • lm78-i2c-0-2d *-i2c-0-2d
  • lm78-i2c-0-* *-i2c-0-*
  • lm78-i2c-*-2d *-i2c-*-2d
  • lm78-i2c-*-* *-i2c-*-*
  • lm78-isa-0290 *-isa-0290
  • lm78-isa-* *-isa-*
  • lm78-*

Monitoring Switch Hardware Using SNMP

The Net-SNMP documentation has been moved to a new chapter, available here.

Monitoring System Units Using smond

The smond daemon monitors system units like power supply and fan, updates their corresponding LEDs, and logs the change in the state. Changes in system unit state are detected via the cpld registers. smond utilizes these registers to read all sources, which impacts the health of the system unit, determines the unit’s health, and updates the system LEDs.

Use smonctl to display sensor information for the various system units:

cumulus@switch:~$ smonctl
Board                                             :  OK
Fan                                               :  OK
PSU1                                              :  OK
PSU2                                              :  BAD
Temp1     (Networking ASIC Die Temp Sensor       ):  OK
Temp10    (Right side of the board               ):  OK
Temp2     (Near the CPU (Right)                  ):  OK
Temp3     (Top right corner                      ):  OK
Temp4     (Right side of Networking ASIC         ):  OK
Temp5     (Middle of the board                   ):  OK
Temp6     (P2020 CPU die sensor                  ):  OK
Temp7     (Left side of the board                ):  OK
Temp8     (Left side of the board                ):  OK
Temp9     (Right side of the board               ):  OK

Command Options

Usage: smonctl [OPTION]... [CHIP]...

Option Description
-s SENSOR, –sensor SENSOR Displays data for the specified sensor.
-v, –verbose Displays detailed hardware sensors data.

For more information, read man smond and man smonctl.

Keeping the Switch Alive Using the Hardware Watchdog

Cumulus Linux includes a simplified version of the wd_keepalive(8) daemon from the standard Debian package watchdog. wd_keepalive writes to a file called /dev/watchdog periodically to keep the switch from resetting, at least once per minute. Each write delays the reboot time by another minute. After one minute of inactivity where wd_keepalive doesn’t write to /dev/watchdog, the switch resets itself.

The watchdog is enabled by default on QuantaMesh BMS T1048-LB9 switches only; you must enable the watchdog on all other switch platforms. When enabled, it starts when you boot the switch, before switchd starts.

To enable the hardware watchdog, edit the /etc/watchdog.d/<your_platform> file and set run_watchdog to 1:


To disable the watchdog, edit the /etc/watchdog.d/<your_platform> file and set run_watchdog to 0:


Then stop the daemon:

cumulus@switch:~$ sudo service wd_keepalive stop

You can modify the settings for the watchdog — like the timeout setting and scheduler priority — in its configuration file, /etc/watchdog.conf.

Configuration Files

  • /etc/cumulus/switchd.conf
  • /etc/cumulus/sysledcontrol.conf
  • /etc/sensors.d/<switch>.conf - sensor configuration file (do not edit it!)
  • /etc/watchdog.conf