Hello Daley
Spectrum can only display what information is provided by supported MIBs on the device. If the device MIB provides Hard Drive Serial Number, and the MIB is imported in Spectrum MIB Tools, then Spectrum should be able to display it. You will want to check with the vendor to determine what MIB / OID provides the HD Serial, if the vendor supports it.
once you have the proper OID, you can use MIB Tool utility to look up the OID, run a SNMP Get on the OID and review the results. Tools > Utilities > MIB Tools.
Or, Spectrum ships with an SNMP Walk utility you can run a walk on the device and dump into a snmpwalk.out file for review. SNMP walk utility is located: <SPECROOT>/bin/SAPWALK2.exe
Regards,
Jay V