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32 .\" @(#)abs.ms 6.2 (Berkeley) 4/16/91
36 Performance Effects of Disk Subsystem Choices
37 for VAX\(dg Systems Running 4.2BSD UNIX*
46 Berkeley, California 94710
48 Marshall Kirk McKusick\(dd
50 Computer Systems Research Group
51 Computer Science Division
52 Department of Electrical Engineering and Computer Science
53 University of California, Berkeley
57 \(dgVAX, UNIBUS, and MASSBUS are trademarks of Digital Equipment Corporation.
60 * UNIX is a trademark of Bell Laboratories.
63 \(ddThis work was supported under grants from
64 the National Science Foundation under grant MCS80-05144,
65 and the Defense Advance Research Projects Agency (DoD) under
66 Arpa Order No. 4031 monitored by Naval Electronic System Command under
67 Contract No. N00039-82-C-0235.
69 Measurements were made of the UNIX file system
70 throughput for various I/O operations using the most attractive currently
71 available Winchester disks and controllers attached to both the
72 native busses (SBI/CMI) and the UNIBUS on both VAX 11/780s and VAX 11/750s.
73 The tests were designed to highlight the performance of single
74 and dual drive subsystems operating in the 4.2BSD
79 Many of the results of the tests were initially counter-intuitive
80 and revealed several important aspects of the VAX implementations
81 which were surprising to us.
83 The hardware used included two Fujitsu 2351A
85 disk drives on each of two foreign-vendor disk controllers
86 and two DEC RA-81 disk drives on a DEC UDA-50 disk controller.
87 The foreign-vendor controllers were Emulex SC750, SC780
88 and Systems Industries 9900 native bus interfaced controllers.
89 The DEC UDA-50 controller is a UNIBUS interfaced, heavily buffered
90 controller which is the first implementation of a new DEC storage
91 system architecture, DSA.
93 One of the most important results of our testing was the correction
94 of several timing parameters in our device handler for devices
95 with an RH750/RH780 type interface and having high burst transfer
97 The correction of these parameters resulted in an increase in
98 performance of over twenty percent in some cases.
99 In addition, one of the controller manufacturers altered their bus
100 arbitration scheme to produce another increase in throughput.
107 .tl '\\*(LH'\\*(CH'\\*(RH'
114 .\".if t .ds CF July 27, 1983
115 .\".if t .ds LF CSRG TR/8
116 .\".if t .ds RF Kridle, et. al.
118 .B "TABLE OF CONTENTS"
127 2.1. DEC UDA50 disk controller
128 2.2. Emulex SC750/SC780 disk controllers
129 2.3. Systems Industries 9900 disk controller
130 2.4. DEC RA81 disk drives
131 2.5. Fujitsu 2351A disk drives
168 .if t .ta .6i 2.1i 2.6i
169 .\" 2.94 went to 2.6, 3.64 to 3.30
170 .if n .ta .84i 2.6i 3.30i
173 .if t .ta .5i 1.25i 2.5i
174 .\" 3.5i went to 3.8i
175 .if n .ta .7i 1.75i 3.8i