Which of the following is not a preventive maintenance measure?

Among the options provided, "data recovery" is not a preventive maintenance measure. Preventive maintenance measures are steps taken to prevent or minimize the occurrence of faults or problems in a system. Regular update of the operating system ensures that the system is up to date with the latest security patches and bug fixes, which helps prevent security vulnerabilities and system crashes. Proper shutdown of the system helps prevent data corruption and hardware failure. The use of uninterrupted power supply (UPS) helps protect the system from power surges and sudden power outages, which can cause data loss or hardware damage. Data recovery, on the other hand, is a corrective measure taken after data loss has already occurred. It involves recovering lost or damaged data from backup or other recovery methods. While important, data recovery is not a preventive maintenance measure, as it does not prevent the loss of data in the first place.