Reference Guide

Mini Core Dumps
Dell Networking OS supports mini core dumps for kernel crashes. The mini core dump applies to Master
units.
Kernel mini core dumps are always enabled. The mini core dumps contain the stack space and some
other very minimal information that can be used to debug a crash. These files are small files and are
written into flash until space is exhausted. When the flash is full, the write process is stopped.
A mini core dump contains critical information in the event of a crash. Mini core dump files are located in
flash://CORE_DUMP_DIR directory. The kernel mini core filename format is
f10StkUnit<stack_unit_no>.kcore.mini.txt.
The panic string contains key information regarding the crash. Several panic string types exist, and they
are displayed in regular english text to enable easier understanding of the crash cause.
Example of a Mini Core Text File
VALID MAGIC
------------------------PANIC STRING -----------------
panic string is : <null>
----------------------STACK TRACE START---------------
0035d60c <f10_save_mmu+0x120>:
00274f8c <panic+0x144>:
0024e2b0 <db_fncall+0x134>:
0024dee8 <db_command+0x258>:
0024d9c4 <db_command_loop+0xc4>:
002522b0 <db_trap+0x158>:
0026a8d0 <mi_switch+0x1b0>:
0026a00c <bpendtsleep>:
------------------------STACK TRACE END----------------
---------------------------FREE MEMORY---------------
uvmexp.free = 0x2312
Enabling TCP Dumps
TCP dump captures CPU bound control plane traffic to improve troubleshooting and system
manageability.
When you enable TCP dumps, a dump captures all the packets on the local CPU, as specified in the CLI.
You can save the traffic capture files to flash, to FTP, SCP, or TFTP. The files saved on the flash are located
in the flash://TCP_DUMP_DIR/Tcpdump_<time_stamp_dir>/ directory and are labeled tcpdump_*.pcap.
There can be up to 20 tcpdump_<time_stamp_dir> directories. The file after 20 overwrites the oldest
saved file. The maximum file size for a TCP dump capture is 1MB. When a file reaches 1MB, a new file is
created, up to the specified total number of files.
Maximize the number of packets recorded in a file by specifying the snap-length to capture the file
headers only.
The tcpdump command has a finite run process. When you enable the command, it runs until the
capture-duration timer and/or the packet-count counter threshold is met. If you do not set a threshold,
the system uses a default of 5 minute capture-duration and/or a single 1k file as the stopping point for
the dump.
916
Z-Series Debugging and Diagnostics