LT-TCO: A TCO Calculation Model of Data Centers for Long-Term Data Preservation

Data centers have been becoming public utilities to provide large-scale computing and storage services. The Total Cost of Ownership (TCO) models for such data centers are paramount to deeply understand their cost of investment and maintenance, the cost composition of internal components, and further cost optimization directions. Existing data center TCO models focus on either high-performance data centers or key subsystems such as IT facility, lacking of holistic analysis of the data centers designed for long-term data preservation. The long-term data centers can be built with different combinations of storage media such as HDDs, tapes, and optical discs. Meanwhile, during the long operation period, devices replacement and data migration are necessary and are not negligible in cost. In order to comprehensively and quantitatively understand the cost of long-term data preservations, we proposed LT-TCO, a TCO calculation model for data centers over time. LT-TCO simulates the construction and operation of a data center to calculate the expenditure of each year. It also introduces the cost of devices replacement and data migration during the long running period. Based on the storage media as optical discs, tapes, HDDs, and SSDs, LT-TCO evaluates the corresponding capital and operational expenditure under different developing rates. The simulation result shows that in long-term preservation, data migration cost takes more than 96% of the operational expenditure. And the TCO of optical disc data centers could be the least among four storage media.