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System Troubleshooting

Saving Core Files Generated by Junos OS Processes

By default, when an internal Junos OS process generates a core file, the file and associated context information are saved for debugging purposes in a compressed tar file named /var/tmp/process-name.core.core-number.tgz. The contextual information includes the configuration and system log message files.

  • To disable the saving of core files and associated context information:

  • To save the core files only:

    Where number is the number of core files to save and can be a value from 1 through 10.

  • To save the core files along with the contextual information:

Viewing Core Files from Junos OS Processes

When an internal Junos OS process generates a core file, you can find the output at /var/crash/ and /var/tmp/. For Junos OS Evolved, you can find the output core files at /var/core/ for Routing Engine core files and /var/lib/ftp/in/ for FPC core files. Using these directories provides a quick method of finding core issues across large networks.

Use the CLI command show system core-dumps to view core files.

See Also

Collect System-State Counters to Capture Information for System Debugging

You can collect and archive system-state counters on your network device. When you request help from JTAC in debugging an issue on your system, you and your JTAC support team can see what was happening on your system at periodic instances before the system issue occurred.

Network devices that support this feature run a shell script that periodically collects RE, PFE, and SHELL counters and other system-state counters. The counters are either protocol-related or CPU-related. The collected counters are saved in counter.log files in the var/log directory. A counter.info file in the same directory records settings for script-execution parameters.

The counters are written in the counter.log file with timestamps, which are helpful in the debugging process.

You have two ways to customize the script's execution:

  1. You can change default script-execution parameter values by editing the counter.info file. You must be logged in as super-user to do this task. See How to Change Script-Execution Parameter Values.

  2. You can restart and then later stop the script's execution. Typically you would do this because the counter.info file was deleted or edited. See How to Restart or Stop the Script's Execution.

What's In the Shell Script and How Does It Run?

Two sets of counters are collected periodically:

  • SET1— This set collects system state for time-sensitive applications periodically at fast intervals of 9 seconds.

  • SET2— This set collects system state periodically at slow intervals of 60 minutes.

The software checks CPU usage before it starts collecting SET1 and SET2 counters. If the software detects high CPU usage (85 percent or more), it does not collect the usually specified counters—instead it collects different counters that make up a smaller set than the set of usually specified counters.

Here's how the script runs:

  1. The shell script starts running 240 seconds after bootup of the network device.

  2. SET1 runs first.

  3. If any command in SET1 doesn't finish in the allotted time, the script truncates the run of that command, saving the CLI output collection to the counter.log file and moving on to the next command.

  4. When SET1's run is finished, SET2 kicks off. Again, any command not finished in the allotted time is truncated, with the CLI output collection saved to the counter.log file and the script moving on to the next line item.

  5. If the script run is restarted or stopped during any CLI output collection, the script completes the ongoing CLI output collection and then exits gracefully.

Note: You cannot change the contents of the shell script itself. You can log in as super-user and then edit the script's execution parameters, including the CLI lists of SET1 and SET2. See How to Change Script-Execution Parameter Values .

How to Change Script-Execution Parameter Values

You can change shell script-execution parameter values—such as the CLI lists for SET1 and SET2 or the number of log files to be archived. You must be logged in as super-user to make changes to the parameter values.

Table 1 lists the parameter settings that you can edit in the counter.info file.

Table 1: Shell Script-Execution Parameter Settings
Setting Description Default Usage Notes
SET1_TIME Time interval to run SET1 collection of line items, at fast time intervals (in seconds) 9 seconds Set to < SET2_TIME
SET2_TIME Time interval to run SET2 collection of line items,at slow time intervals (in seconds) 3600 seconds Set to > SET1_TIME
MAX_CLI_EXECUTION_TIME Maximum time interval (in seconds) to wait for the completion of each CLI output collection 25 seconds If CLI output collection takes longer than this time, the script terminates that specific CLI output collection and executes the next statement in the script. This behavior ensures that the script executes all statements.
SET1_ON For enabling and disabling fast counter collection 1 (enable)  
SET2_ON For enabling and disabling slow counter collection 1 (enable)  
LOG_FILE_ARCHIVE_MIN_SIZE Minimum size of counter.log file to be archived 1024k  
LOG_FILE_ARCHIVE_COUNT Number of counter.log files to be archived 10  
VERSION Version number of the counter.info file  
CAUTION:
Do not update the VERSION value in the /var/log/counter.infofile.
SET1 and SET2 CLI lists of commands that are run in the script The CLI lists are broken into the following sublists:

  • SET1_RE

  • SET2_RE

  • SET1_PFE

  • SET2_PFE

  • SET1_SHELL

  • SET2_SHELL

Note: If CPU utilization is detected as >85%,outputs of CLI mentioned in RE_CPU, PFE_CPU,and SHELL_CPU are collected at the intervals of SET1_TIME and SET2_TIME.
 Each set comes with a default list of CLI commands. If the default CLI lists don't provide all the system information you need, edit the CLI lists to obtain counters for the additional system information that you require.

How to Restart or Stop the Script's Execution

If you make changes in the counter.info file, use the restart command to run the script manually:

Use the stop command to stop the script's run: