serialnum - system serial number file
/etc/serialnum
The file /etc/serialnum should contain the serial number of your machine. The serial number is found on the back of the machine in the lower right hand corner. You should see a tag that says:
NetworkAppliance SN: xxxx
If the file does not exist on your system, please create it and put the machine's serial number in it. The file should contain a single line that only has the serial number. The file is used to help Network Appliance's customer service group process your autosupport email more efficiently.
/etc/serialnum