A vital product data system memory stores warranty information in vital product data relating to replaceable unit(s) of a data handling system. The data comprises a date of first use, and a device state field comprising an identifier representing one of the states: "new", "recertified", and, "in-use". Management control, in response to newly sensing a replaceable unit, detects its device state field, and if the detected field is set to the "new" state, resets it to the "in-use" state, sets the date of first use to a current date, and stores the state field and date of first use for the replaceable unit in the memory; and if the detected field is set to the "recertified" state, resets the field to the "in-use" state, and sets the replaceable unit date of first use to the date of first use stored in the memory for the previous replaceable unit at the same location.