1000-9825/2002/13(02)0239-06 2002 Journal of Sofware Vol13, No2 -,, (, 100084) E-mail: shijing@mailssinghuaeducn; xingcx@singhuaeducn; dcszlz@singhuaeducn hp://dbgroupcssinghuaeducn : 10 12,, I/O -, -,,, : ; I/O ; - : TP316 : A, [1] 10 12 (erabye),,, [2],,, I/O [3~6], [3] DLT, [4] [5] I/O, [6] ( ),,,,,,, (1),, ;(2) : 2001-04-20; : 2001-09-05 : 973 (G1999032704) : (1969 ),,,, ; (1967 ),,,, ; (1947 ),,,,Web
240 Journal of Sofware 2002,13(2),,,,,, -,,, Elian 820 Exabye 220, 1 2-3 4 5 1 - (1),, (2) 3~4,, (3),,,, (1) (2),, (3),,,,, -,, ( 60/40, 60% 40%, 80/20 ), ;,,,,,,,, ( 20% ),,,,, -,,,, (round robin),,, -, ( (MB) ( ) ),,, ;,,, ( ): E = W bw S S + W T w avg T avg (1),E, E S,T, S avg,t avg,
: - 241, W bw,w w,, -, 2-1, - W bw W w,,, 3 21 3 -,, 4, - 3 w (1) - R w/b ( R / = ), w b,, ( ), ( ),, - R w/b (2),R w/b 1 20, ( 08~12), W Wbw Mean response ime (s) 6440 6400 6360 6320 6280 0 0 06 12 18 24 3 36 42 0 05 1 15 2 25 3 35 4 Weigh raio of wai ime and effecive bandwidh Requess per minue,, / Weigh raio (%) 280 240 200 160 120 80 40 Fig1 Impac of weigh raio on response Fig2 Relaionship of Weigh raio and workload 1 2 (3) R w/b R w/b, 2,,,,, 22 3 -, (1)
242 Journal of Sofware 2002,13(2) S E = 1 S avg + R w/ b T T avg (2), R w/b, R w/b 0 < 09 R w / b = 09,λ, λ ;S 16000 (MB);TR (MB/ Opimal value 14000 ),N,60 Esimaion value, 12000 Mean response ime (s),- 10000 -, 8000, 60λ TR S N <09,R w/b 6000 4%, R w/b 1%,, 4000,R w/b 0, 1% 14 18 22 26 3 34 38 42 09,R w/b Requess per minue, /,, 1%, Fig3 Performance comparison for esimaion value 1% 3 R w/b and opimal value of R w/b R w/b ( 3 R w/b ), 64M, 70/10 3 R w/b 3 -,, :U R,U,R U, R, ( ) (1), ;, (2),, U, ; R TQ (3) TQ,,, (4) (3) R w/b ; S avg T avg ; S T, (2) - (3) Elian 820, ; DTL, [3]
: - 243 (5) - L max,, L nex, L max, L max,, (2) U, (3) R,,, ;, 4 - Exabye 220 Elian 820 EXABTYE 8mm,, 1 2 1 20 Table 1 Measuremen of ape library Exabye 220 1 Exabye 220 TAPE (20) Capaciy 7GB(uncompressed ) TAPE DRIVE (2) TAPE ROBOT (1) Daa ransfer rae Mean drive load ime Mean drive ejec ime Rewind sarup ime Rewind rae Seek sarup ime Seek rae 092MB/s (uncompressed) 25s 23s 7s 22MB/s 85s 302MB/s (uncompressed) Mean ape unload ime Mean ape load ime 72s,,,,,,,,,, 742s Mean response ime (s) 16000 14000 12000 10000 8000 6000 Max-Effecive-Bandwidh -Based scheduling Benefi-Cos-Based scheduling 4000 14 18 22 26 3 34 38 42 Requess per minue,, - Fig4 Benefi-Cos-Based scheduling 4-4 - 4,
244 Journal of Sofware 2002,13(2) >15, -, 15, 2, - 1%,, R w/b 0,, 2 5 -, -, - References: [1] Cariño, F, Kaufmann, A, Kosamaa, P Are you ready for Yoabyes? In: Kobler, B, ed Proceedings of he 17h IEEE Symposium on Mass Sorage Sysems in Cooperaion wih he 8h NASA GSFC Conference on Mass Sorage Sysems and Technologies Los Alamiors, CA: IEEE Compuer Sociey Press, 2000 476~485 [2] Cariño, F, Burgess, J, O Connell, W, e al Acive sorage hierarchy, daabase sysems and applicaions socraic exegesis In: Malcolm, PA, Maria, EO, e al, eds Proceedings of he 25h Inernaional Conference on Very Large Daa Bases Edinburgh: Morgan Kaufmann Publishers, Inc, 1999 611~614 [3] Hillyer, BK, Silberschaz, A Random I/O scheduling in online eriary sorage sysems In: Jagadish, HV, Mumick, IS, eds Proceedings of he 1996 ACM SIGMOD Inernaional Conference on Managemen of Daa Quebec: ACM Press, 1996 195~204 [4] Trianafillou, P, Georgiadis, I Hierarchical scheduling algorihms for near-line ape libraries In: Cammelli, A, Wagner, R R, eds Proceedings of he 10h Inernaional Conference and Workshop on Daabase and Exper Sysems Applicaions Florence: IEEE Compuer Sociey Press, 1999 50~54 [5] Hillyer, B K, Rasogi, R, Silberschaz, A Scheduling and daa replicaion o improve ape jukebox performance In: Papazoglou, M, Pu, C, Kisuregawa, M, eds Proceeding of he 15h Inernaional Conference on Daa Engineering Sydney: IEEE Compuer Sociey Press, 1999 532~541 [6] Nemoo, T, Kisuegawa, M Scalable ape archiver for saellie image daabase and is performance analysis wih access logs ho declusering and ho replicaion In: Miller, E, ed Proceedings of he 16h IEEE Symposium on Mass Sorage Sysems in Cooperaion wih he 7h NASA GSFC Conference on Mass Sorage Sysems and Technologies San Diego: IEEE Compuer Sociey Press, 1999 59~71 A Cos-Benefi-Based Scheduling Algorihm of Online Tape Library SHI Jing, XING Chun-xiao, ZHOU Li-zhu (Deparmen of Compuer Science and Technology, Tsinghua Universiy, Beijing 100084, China) E-mail: shijing@mailssinghuaeducn; xingcx@singhuaeducn; dcszlz@singhuaeducn hp://dbgroupcssinghuaeducn Absrac: The erabye-level (10 12 byes) daabase sysems such as digial libraries need o use ape library as an online device o sore and rerieve heir massive daa Since he access of a ape library is ofen random and he ape library has low random access performance, hus i is criical o sudy he random I/O scheduling sraegies and algorihms in order o improve he performance of ape library In his paper we sudy a cos-benefi-based scheduling algorihm, and as well as give an effecive esimaing mehod of cos-benefi weigh raio This algorihm improves he performance of ape library sysem under differen workloads by dynamically uning he cos-benefi weigh raio of scheduling policies according o workloads This algorihm paricularly overcomes he problem of workload-sensiive of exising scheduling algorihms, and is significanly effecive under heavy workload Key words: online ape library sysem; random I/O scheduling of apes; ho daa replicaion; cos-benefi esimaing Received April 20, 2001; acceped Sepember 5, 2001 Suppored by he Naional Grand Fundamenal Research 973 Program of China under Gran NoG1999032704