On a UNIX platform (Like Juniper devices) if a process is hung or having issues it is possible to force the application to write the memory image; known as a core dump. This core dump can then later be analyzed by Juniper Technical Assistance Center (JTAC) to determine a possible root cause of the hang or a possible bug or software issue
A process application (like pfed, chassisd, l2ald, etc) might hung, not response or have issues
1. Get in to shell (you need root access):
user@Juniper-MX-1> start shell user root Password: root@Juniper-MX-1%
2. Locate the process ID, known as PID, which needs to generate a core dump
# ps ax | grep <process-name> | grep -v grep
The PID number will be the first number listed in the output
Example:
root@Juniper-MX-1% ps ax | grep chassisd | grep -v grep 1303 ?? S 540:46.58 /usr/sbin/chassisd -N
3. Create the core-dump using the following command:
root@Juniper-MX-1% gcore -s -c /var/tmp/chassisd-core-test1.core 1303
4. Verify that core-dump was properly generated
jmiranda@Juniper-MX-1> show system core-dumps | match chassisd-core-test1 -rw-r--r-- 1 root field 11829248 Dec 3 12:03 /var/tmp/chassisd-core-test1.core