Hard disk drives returned back to Seagate undergo the Field Return Incoming Test. During the test, the available logs in disk drives are collected, if possible. These logs contain cumulative data on the workload seen by the drive during its lifetime, including the amount of bytes read and written, the number of completed seeks, and the number of spin-ups. The population of returned drives is considerable and the respective collected data represents a good source of information n disk drive workloads. In this paper, we present an in-breadth analysis of these logs for the Cheetah 10K and 15K families of drives. We observe that over an entire family of drives, the workload behavior is variable. The workload variability is more enhanced during the first month of the drive's life than afterward. Our analysis shows that the drives are generally underutilized. Yet, there is a portion of them, about 10%, that experience higher utilization levels. Also, the data sets indicate that the maj...