Monitoring and Troubleshooting
This chapter introduces the basics for monitoring and troubleshooting Cumulus Linux.
Serial Console
Use the serial console to debug issues if you reboot the switch often or if you do not have a reliable network connection.
The default serial console baud rate is 115200, which is the baud rate ONIE uses.
Configure the Serial Console
On x86 switches, you configure serial console baud rate by editing grub.
Incorrect configuration settings in grub cause the switch to be inaccessible through the console. Review grub changes before you implement them.
The valid values for the baud rate are:
- 300
- 600
- 1200
- 2400
- 4800
- 9600
- 19200
- 38400
- 115200
To change the serial console baud rate:
-
Edit the
/etc/default/grubfile and provide a valid value for the--speedandconsolevariables:GRUB_SERIAL_COMMAND="serial --port=0x2f8 --speed=115200 --word=8 --parity=no --stop=1" GRUB_CMDLINE_LINUX="console=ttyS1,115200n8 cl_platform=accton_as5712_54x" -
After you save your changes to the grub configuration, type the following at the command prompt:
cumulus@switch:~$ update-grub -
If you plan on accessing the switch BIOS over the serial console, you need to update the baud rate in the switch BIOS. For more information, see this knowledge base article.
-
Reboot the switch.
Change the Console Log Level
By default, the console prints all log messages except debug messages. To tune console logging to be less verbose so that certain levels of messages do not print, run the dmesg -n <level> command, where the log levels are:
| Level | Description |
|---|---|
| 0 | Emergency messages (the system is about to crash or is unstable). |
| 1 | Serious conditions; you must take action immediately. |
| 2 | Critical conditions (serious hardware or software failures). |
| 3 | Error conditions (often used by drivers to indicate difficulties with the hardware). |
| 4 | Warning messages (nothing serious but might indicate problems). |
| 5 | Message notifications for many conditions, including security events. |
| 6 | Informational messages. |
| 7 | Debug messages. |
Only messages with a value lower than the level specified print to the console. For example, if you specify level 3, only level 2 (critical conditions), level 1 (serious conditions), and level 0 (emergency messages) print to the console:
cumulus@switch:~$ sudo dmesg -n 3
You can also run dmesg --console-level <level> command, where the log levels are emerg, alert, crit, err, warn, notice, info, or debug. For example, to print critical conditions, run the following command:
cumulus@switch:~$ sudo dmesg --console-level crit
The dmesg command applies until the next reboot.
For more details about the dmesg command, run man dmesg.
Show System Information
Cumulus Linux provides commands to obtain system information and to show the version of Cumulus Linux you are running. Use these commands when performing system diagnostics, troubleshooting performance, or submitting a support request.
To show information about the version of Cumulus Linux running on the switch, run the nv show system command:
cumulus@switch:~$ nv show system
operational applied
----------------- ------------------- -------
uptime 23:22:36
hostname cumulus cumulus
product-name Cumulus Linux
contact
location
dns
domain
date-time
local-time 2025-10-02 11:42:53
timezone Etc/UTC Etc/UTC
health
status Not OK
version
product-release 5.15.0
global
system-mac 44:38:39:22:01:b1 auto
anycast-mac none none
To show system memory information in bytes, run the nv show system memory command:
cumulus@switch:~$ nv show system memory
B - Bytes, KB - Kilobytes, MB - Megabytes, GB - Gigabytes, % - Percent
Physical total: 1.67 GB
Physical free: 406.38 MB
Physical buffer: 37.19 MB
Physical cache: 222.11 MB
Physical used: 1.20 GB
Physical utilization: 72.05 %
Swap total: 0 B
Swap free: 0 B
Swap used: 0 B
Swap utilization: 0.00 % 0 B 0 B 0 B 0.0%
To show system CPU information, run the nv show system cpu command:
cumulus@switch:~$ nv show system cpu
operational
----------------- -----------------------------
model QEMU Virtual CPU version 2.5+
core-count 1
total-utilization 0.3%
load-average
one-minute 0.02
five-minute 0.02
fifteen-minute 0.0
Cores
========
CPU Utilization
---- -----------
CPU0 100.0%
To show general information about the switch, run the nv show platform command:
cumulus@switch:~$ nv show platform
operational
------------- ---------------------------------------
system-mac 44:38:39:22:01:b1
manufacturer Cumulus
cpu x86_64 QEMU Virtual CPU version 2.5+ x1
memory 1.67 GB
disk-size n/a
port-layout n/a
part-number 5.15.0
serial-number 44:38:39:22:01:7a
asic-model n/a
system-uuid 51c411e8-43d2-4e60-a7e7-e068aa04b7f9
system-type VX
Diagnostics Using a cl-support File
You can generate a single export cl-support file that contains various details about switch configuration, and is useful for remote debugging and troubleshooting.
Generate a cl-support file to investigate issues before you submit a support request. You can either run the NVUE nv action generate system tech-support command or the Linux sudo cl-support command:
cumulus@switch:~$ nv action generate system tech-support
...
For more information, refer to Understanding the cl-support Output File.