Performance Measurements of Tertiary Storage Devices

In spite of the rapid decrease in magnetic disk prices, tertiary storage (i.e., removable media in a robotic storage library) is becoming increasingly popular. The fact that so much data can be stored encourages applications that use ever more massive data sets. Application drivers include multimedia databases, data warehouses, scientific databases, and digital libraries and archives. The database research community has responded with investigations into systems integration, performance modeling, and performance optimization. Tertiary storage systems present special challenges because of their unusual performance characteristics. Access latencies can range into minutes even on unloaded systems, but transfer rates can be very high. Tertiary storage is implemented with a wide array of technologies, each with its own performance quirks. However, little detailed performance information about tertiary storage devices has been published. In this paper we present detailed measurements of several tape drives and robotic storage libraries. The tape drives we measure include the DLT 4000, DLT 7000, Ampex 310, IBM 3590, 4mm DAT, and the Sony DTF drive. This mixture of equipment includes high and low performance drives, serpentine and helical scan drives, and cartridge Permission to copy without fee all or part oj this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires a fee and/or special permission from the Endowment. Proceedings of the 24th VLDB Conference New York, USA, 1998 Ethan L. Miller [email protected] CSEE Department University of Maryland, Baltimore County Baltimore, MD 21250 and cassette tapes. The detailed measurements of different aspects of tertiary storage system performance provides an understanding of the issues related to integrating tapebased tertiary storage with a DBMS.