caa a22 4500 465821464 CHVBK 20180323112136.0 cr unu---uuuuu 170327e19900601xx s 000 0 eng 10.1007/BF02017343 doi (NATIONALLICENCE)springer-10.1007/BF02017343 Optimal data placement in two-headed disk systems [Elektronische Daten] [Yannis Manolopoulos, J. Kollias] A problem inherent to the performance of disk systems is the data placement in cyinders in such a way that the seek time is minimized. If successive searchers are independent, then the optimal placement for conventional one-headed disk systems is the organ-pipe arrangement. According to this arrangement the most frequent cylinder is placed in the central location, while the less frequent cylinders are placed right and left alternatively. This paper proves that the optimal placement for two-headed disk systems is the "camel” arrangement, which may be viewed as two consecutive organ-pipe arrangements. It is also proved that, for a two-headed disk system withN=2(2n+1) cylinders, the total number of these optimal camel arrangements is exp2 (N/2+1). BIT Foundations, 1990 D.4.2 nationallicence Algorithms nationallicence Performance nationallicence Camel arrangement nationallicence Data placement nationallicence Organ-pipe arrangement nationallicence Seek distance nationallicence Two-headed disk nationallicence Manolopoulos Yannis Divison of Computer and Electronics Engineering, Department of Electrical Engineering, Aristotelian University of Thessaloniki, 54006, Thessaloniki, Greece aut Kollias J. Divison of Computer and Electronics Engineering, Department of Electrical Engineering, Aristotelian University of Thessaloniki, 54006, Thessaloniki, Greece aut BIT Kluwer Academic Publishers 30/2(1990-06-01), 216-219 0006-3835 30:2<216 1990 30 10543 https://doi.org/10.1007/BF02017343 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02017343 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Manolopoulos Yannis Divison of Computer and Electronics Engineering, Department of Electrical Engineering, Aristotelian University of Thessaloniki, 54006, Thessaloniki, Greece aut NATIONALLICENCE 700 1- Kollias J. Divison of Computer and Electronics Engineering, Department of Electrical Engineering, Aristotelian University of Thessaloniki, 54006, Thessaloniki, Greece aut NATIONALLICENCE 773 0- BIT Kluwer Academic Publishers 30/2(1990-06-01), 216-219 0006-3835 30:2<216 1990 30 10543 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer