Monitoring System Hardware

You can monitor system hardware with the following commands and utilities:

  • NVUE
  • decode-syseeprom
  • smond
  • sensors
  • watchdog

NVUE Commands

You can run NVUE commands to monitor your system hardware.

nv show platformShows platform hardware information on the switch, such as the model and manufacturer, memory, serial number and system MAC address.
nv show platform environment fanShows information about the fans on the switch, such as the minimum, maximum and current speed, the fan state, and the fan direction.
nv show platform environment ledShows information about the LEDs on the switch, such as the LED name and color.
nv show platform environment psuShows information about the PSUs on the switch, such as the PSU name and state.
nv show platform environment temperatureShows information about the sensors on the switch, such as the critical, maximum, minimum and current temperature and the current state of the sensor.
nv show platform environment voltageShows the list of voltage sensors on the switch.
nv show platform inventoryShows the switch inventory, which includes fan and PSU hardware version, model, serial number, state, and type. For information about a specific fan or PSU, run the nv show platform inventory <inventory-name> command.

The following example shows the nv show platform command output:

cumulus@switch:~$ nv show platform
-------------  -----------------
system-mac     44:38:39:22:01:b1                      
manufacturer   Cumulus                                
product-name   VX                                     
cpu            x86_64 QEMU Virtual CPU version 2.5+ x1
memory         1756460 kB                             
disk-size      n/a                                    
port-layout    n/a                                    
part-number    5.9.1                                  
serial-number  44:38:39:22:01:7a                      
asic-model     n/a                                    
system-uuid    e928ee83-20f7-4515-bfab-c204db3e604c

The following example shows the nv show platform environment fan command output. The airflow direction must be the same for all fans. If Cumulus Linux detects that the fan airflow direction is not uniform, it logs a message in the var/log/syslog file.

cumulus@switch:~$ nv show platform environment fan
Name      Fan State  Current Speed (RPM)  Max Speed  Min Speed  Fan Direction
--------  ---------  -------------------  ---------  ---------  -------------
FAN1/1    ok         6000                 29000      2500       F2B         
FAN1/2    ok         6000                 29000      2500       F2B         
FAN2/1    ok         6000                 29000      2500       F2B         
FAN2/2    ok         6000                 29000      2500       F2B         
FAN3/1    ok         6000                 29000      2500       F2B         
FAN3/2    ok         6000                 29000      2500       F2B         
PSU1/FAN  ok         6000                 29000      2500       F2B         
PSU2/FAN  ok         6000                 29000      2500       F2B   

If the airflow direction for all fans is not in the same (front to back or back to front), cooling is suboptimal for the switch, rack, and even the entire data center.

decode-syseeprom Command

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

The following is example decode-syseeprom command output. The output is different on different switches:

cumulus@switch:~$ decode-syseeprom
TlvInfo Header:
   Id String:    TlvInfo
   Version:      1
   Total Length: 69
TLV Name             Code Len Value
-------------------- ---- --- -----
Vendor Name          0x2D  16 Cumulus Networks
Product Name         0x21   2 VX
Device Version       0x26   1 3
Part Number          0x22   5 5.9.1
MAC Addresses        0x2A   2 55
Base MAC Address     0x24   6 44:38:39:22:01:7A
Serial Number        0x23  17 44:38:39:22:01:7a
CRC-32               0xFE   4 0xF305A73F
(checksum valid)

The decode-syseeprom command includes the following options:

-h, -helpDisplays the help message and exits.
-aPrints the base MAC address for switch interfaces.
-rPrints the number of MAC addresses allocated for the switch interfaces.
-sSets the EEPROM content (if the EEPROM is writable). You can provide arguments in the command line in a comma separated list in the form <field>=<value>.
  • . , and = are not allowed in field names and values.
  • Any field not specified defaults to the current value.

NVIDIA Spectrum switches do not support this option.
-j, --jsonDisplays JSON output.
-t <target>Prints the target EEPROM information (board, psu2, psu1).
--serial, -ePrints the device serial number.
-mPrints the base MAC address for the management interfaces.
--initClears and initializes the board EEPROM cache.

Run the sudo dmidecode command to retrieve hardware configuration information populated in the BIOS.


The smond service monitors system units like power supply and fan, updates the corresponding LEDs, and logs the change in state. The cpld registers detect changes in system unit state. smond utilizes these registers to read all sources, which determines the health of the unit and updates the system LEDs.

Run the sudo smonctl command to display sensor information for the various system units:

cumulus@switch:~$ sudo smonctl
Fan1      (Fan Tray 1, Fan 1                     ):  OK
Fan2      (Fan Tray 1, Fan 2                     ):  OK
Fan3      (Fan Tray 2, Fan 1                     ):  OK
Fan4      (Fan Tray 2, Fan 2                     ):  OK
Fan5      (Fan Tray 3, Fan 1                     ):  OK
Fan6      (Fan Tray 3, Fan 2                     ):  OK
PSU1                                              :  OK
PSU2                                              :  OK
PSU1Fan1  (PSU1 Fan                              ):  OK
PSU1Temp1 (PSU1 Temp Sensor                      ):  OK
PSU2Fan1  (PSU2 Fan                              ):  OK
PSU2Temp1 (PSU2 Temp Sensor                      ):  OK
Temp1     (Board Sensor near CPU                 ):  OK
Temp2     (Board Sensor Near Virtual Switch      ):  OK
Temp3     (Board Sensor at Front Left Corner     ):  OK
Temp4     (Board Sensor at Front Right Corner    ):  OK
Temp5     (Board Sensor near Fan                 ):  OK

When the switch is not powered on, smonctl shows the PSU status as BAD instead of POWERED OFF or NOT DETECTED. This is a known limitation.

The smonctl command includes the following options:

Option Description
-s <sensor>, --sensor <sensor>Displays data for the specified sensor.
-v, --verboseDisplays detailed hardware sensors data.

The following command example shows information about FAN6 on the switch:

cumulus@switch:~$ smonctl -s FAN6 -v
Fan6      (Fan Tray 3, Fan 2                     ):  OK

For more information, read man smond and man smonctl.

sensors Command

Run the sensors command to monitor the health of your switch hardware, such as power, temperature and fan speeds. This command executes lm-sensors.

Even though you can use the sensors command to monitor the health of your switch hardware, NVIDIA recommends you use the smond daemon to monitor hardware health. See smond Daemon above.

For example:

cumulus@switch:~$ sensors
Adapter: ISA adapter
fan1:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
fan2:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
fan3:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
fan4:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
fan5:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
fan6:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
fan7:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
fan8:        6000 RPM  (min = 2500 RPM, max = 29000 RPM)
temp1:        +25.0°C  (low  =  +5.0°C, high = +80.0°C)
                       (crit low =  +0.0°C, crit = +85.0°C)
temp2:        +25.0°C  (low  =  +5.0°C, high = +80.0°C)
                       (crit low =  +0.0°C, crit = +85.0°C)
temp3:        +25.0°C  (low  =  +5.0°C, high = +80.0°C)
                       (crit low =  +0.0°C, crit = +85.0°C)
temp4:        +25.0°C  (low  =  +5.0°C, high = +80.0°C)
                       (crit low =  +0.0°C, crit = +85.0°C)
temp5:        +25.0°C  (low  =  +5.0°C, high = +80.0°C)
                       (crit low =  +0.0°C, crit = +85.0°C)
temp6:        +25.0°C  (low  =  +5.0°C, high = +80.0°C)
                       (crit low =  +0.0°C, crit = +85.0°C)
temp7:        +25.0°C  (low  =  +5.0°C, high = +80.0°C)
                       (crit low =  +0.0°C, crit = +85.0°C)

  • Output from the sensors command varies depending upon the switch.
  • If you only plug in one PSU, the fan is at maximum speed.

The following table shows the sensors command options.

-c --config-fileSpecify a configuration file; use - after -c to read the configuration file from stdin; by default, sensors references the configuration file in /etc/sensors.d/.
-s --setExecute set statements in the configuration file (root only); sensors -s runs one time at boot and applies all the settings to the boot drivers.
-f --fahrenheitShow temperatures in degrees Fahrenheit.
-A --no-adapter
-A --bus-list
Do not show the adapter for each chip.
Generate bus statements for sensors.conf.
-uGenerate raw output.
-jGenerate json output.
-vShow the program version.

Hardware Watchdog

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

Cumulus Linux enables the watchdog by default, which starts when you boot the switch (before switchd starts).

To disable the watchdog, disable and stop the wd_keepalive service:

cumulus@switch:~$ sudo systemctl disable wd_keepalive ; systemctl stop wd_keepalive 

You can modify the settings for the watchdog, such as the timeout and the scheduler priority, in the /etc/watchdog.conf configuration file.

cumulus@switch:~$ sudo nano /etc/watchdog.conf
watchdog-device	= /dev/watchdog
# Set the hardware watchdog timeout in seconds
watchdog-timeout = 30
# Kick the hardware watchdog every 'interval' seconds
interval = 5
# Log a status message every (interval * logtick) seconds.  Requires
# --verbose option to enable.
logtick = 240
# Run the daemon using default scheduler SCHED_OTHER with slightly
# elevated process priority.  See man setpriority(2).
realtime = no
priority = -2