We tried to run GRloader with input file with these four fields: resource_name, serial_number, family, class. We wanted to update the serial_number using the value in resource_name. GRloader didn't update the configuration item. Instead, it skipped it:
Results:
Read Skipped Inserts Updates Errors Warnings
CI 1 1 0 0 0 0
Relation 0 0 0 0 0 0
CA Service Desk Manager/CMDB all versions
You can't use the resource_name to update serial_number via GRloader.
According to CORA registration(see link CORA in Additional Information), CORA registration uses
label, host_name, serial_number, asset_tag, mac_address and dns_name
therefore you can use resource_name to update serial_number via GRloader.
If you don't want the current active configuration item as the serial_number is not valid/needed anymore, you can make it inactive and then use GRloader to create a new configuration item using the new serial_number.