With the advent of cloud computing and online services, large enterprises rely heavily on their datacenters to serve end users. A large datacenter facility incurs increased maintenance costs in addition to service unavailability when there are increased failures. Among different server components, hard disk drives are known to contribute significantly to server failures; however, there is very little understanding of the major determinants of disk failures in datacenters. In this work, we focus on the interrelationship between temperature, workload, and hard disk drive failures in a large scale datacenter. We present a dense storage case study from a population housing thousands of servers and tens of thousands of disk drives, hosting a large-scale online service at Microsoft. We specifically establish correlation between temperatures and failures observed at different location granularities: (a) inside drive locations in a server chassis, (b) across server locations in a rack, and (c) across multiple racks in a datacenter. We show that temperature exhibits a stronger correlation to failures than the correlation of disk utilization with drive failures. We establish that variations in temperature are not significant in datacenters and have little impact on failures. We also explore workload impacts on temperature and disk failures and show that the impact of workload is not significant. We then experimentally evaluate knobs that control disk drive temperature, including workload and chassis design knobs. We corroborate our findings from the real data study and show that workload knobs show minimal impact on temperature. Chassis knobs like disk placement and fan speeds have a larger impact on temperature. Finally, we also show the proposed cost benefit of temperature optimizations that increase hard disk drive reliability.

When datacenters are pushed to their limits of operational efficiency, reducing failure rates becomes critical for maintaining high levels of healthy server operation. In this experience report, we present a dense storage case study from a large population of servers housing tens of thousands of disk drives. Previous studies have presented divergent results concerning correlation between temperature and hard disk drive failures. In our paper, we specifically establish correlation between temperatures and failures observed at different location granularities: a) inside drive locations in a server chassis, b) across server locations in a rack and c) across multiple racks in a datacenter. We also establish that temperature exhibits a stronger correlation to failures compared to the correlation of disk utilization with drive failures. Thus, we show that temperature-aware server and datacenter design plays a pivotal role in datacenter reliability. Following our case study, we present a reliability model for estimating hard disk drive failures correlated with the datacenter operating temperature. We use a physical Arrhenius model with empirically derived coefficients for our model. We show an application of the model for selecting the datacenter inlet temperature setpoint for two different server storage configurations. Finally, with the help of a datacenter cost discussion, we highlight the need to incorporate reliability-aware datacenter design for increased efficiency in large scale datacenters.