Step 1:Because a crash may be imminent can we enable a debug called “debug sanity”, basically this has the switch perform additional checks on its memory. After you apply this please keep an eye on the CPU by doing show process cpu history. If this debug causes a huge spike then please do “undebug sanity”. Also, if the switch reloads this debug will be automatically removed. In the event of a crash we might have more information about what is causing the issue.
Step 2:
Enabling a core dump in the event of a crash:
There are 3 main ways to do it, depending on one's environment and what is easiest.
The easiest way is dumping to flash. Depending on the platform this could be flash: bootflash: or disk0: By default a core dump sent to flash is compressed but you likely need a hundred MB of flash free, depending on the platform. Time required to write a corefile to flash vs. writing a corefile via ftp will vary based on the size of the file. Lab tests show the following times for writing 3.5 GB worth of corefiles:
FLASH*:
1005532950 bytes
248 seconds
4059003 bytes/sec
FTP*:
1006632960 bytes
2051 seconds
490801 bytes/sec
This is with an FTP server on a local segment with average response times around 1 ms, increasing the number of hops or increasing the response time will decrease the performance.
*Actual results may vary*
Instructions for all three methods follow:
FTP:
config t
ip ftp username [login-name]
(optional, not needed if anonymous ftp is enabled on the destination server)
ip ftp password [login-pass]
(optional, not needed if anonymous ftp is enabled on the destination server)
exception protocol ftp
exception region-size 65000
exception dump [ip-address]
(If there is no ftp username/pass it will attempt anonymouse FTP.)
end
write mem
TFTP:
config t
exception protocol tftp
exception region-size 65000
exception dump [ip-address]
end
write mem
Note: Please test FTP/TFTP server configuration to ensure it works correctly.
copy run tftp:
or
copy run ftp:
Then after some prompting you should see something like:
Writing c7600-confg !
2781 bytes copied in 0.944 secs
Flash:
conf t
exception flash all [path]
(bootflash:, disk0:, etc)
Finally, what do you do with the large file that is generated and is too large for email?
Please edit the filename to include your SR Number then you can send the core dump files to Cisco through anonymous FTP.
The FTP server is at the following location (directory /incoming )
ftp-sj.cisco.com
Please respond with feedback if this document assist you or if you feel this document contains inaccuracies or needs additional information.
Thank you,
Brian Hardenstein
Source:
http://w ww.cisco.com/en/US/products/sw/iosswrel/ps1835/products_tech_note09186a00800c7d59.shtml
