Saving the Last Core to Bootflash
This last core dump is automatically saved to bootflash in the /mnt/pss/ partition before the switchover or reboot occurs.
Three minutes after the supervisor module reboots, the saved last core is restored from the flash partition (/mnt/pss) back to its original RAM location.
This restoration is a background process and is not visible to the user.
The timestamp on the restored last core file displays the time when the supervisor booted up not when the last core was actually dumped.
To obtain the exact time of the last core dump, check the corresponding log file with the same PID.
To view the last core information, enter the show cores command in EXEC mode.
To view the time of the actual last core dump, enter the show process log command in EXEC mode.
Reference:
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/mds9000/sw/6_2/configuration/guides/system_management/nx-os/sysmgmt_cli_6-x/sys.html#64619