darrell@sequoia.ucsc.edu (Darrell Long) (09/25/90)
The following results are summarized from "A Study of the Reliability of
Internet Sites" (available as ucsc-crl-90-46.ps.Z from midgard.ucsc.edu).
A large number of hosts were polled using Sun RPC and ICMP echo (ping) to
collect data on mean-time-to-failure, availability and mean-time-to-repair.
More than 100,000 hosts were polled. Of these about 13,000 responded with
useful data.
The details of the measurements and data reduction can be found in the paper.
We welcome comments. Please address them to:
Darrell Long John Carroll
darrell@cis.ucsc.edu carroll@sdsu.edu
Mean-Time-to-Failure for Specific Sun 4 Systems.
Model n min (days) max (days) mean (days) s-dev
4/60 1116 0.009 233.864 16.831 24.259
4/65 39 0.164 31.627 7.340 6.773
4/110 159 0.070 90.363 14.818 17.752
4/280 162 0.019 112.150 13.806 17.921
4/330 41 0.247 153.856 14.811 26.965
4/390 31 0.025 100.295 12.317 21.576
Mean-Time-to-Failure for Specific Sun 3 Systems.
Model n min (days) max (days) mean (days) s-dev
3/50 1730 0.036 330.833 18.687 27.445
3/60 1026 0.006 245.134 18.866 24.164
3/80 242 0.056 148.041 14.707 21.122
3/180 136 0.014 120.378 13.255 19.439
3/280 223 0.017 118.952 16.565 21.130
Mean-Time-to-Failure for Various Systems.
Model n min (days) max (days) mean (days) s-dev
Sun 386i 176 0.070 107.395 19.341 21.150
Sun 4 1735 0.009 233.864 15.679 22.499
Sun 3 4475 0.002 330.833 17.734 25.145
Suns 7205 0.002 330.833 17.115 24.109
Vax 122 0.017 160.534 13.018 20.527
Vax (Vms) 21 0.415 46.282 8.553 12.989
Availability of Specific Sun 4 Systems.
Model n Responses % Available
4/60 1047 975 93.12
4/65 36 34 94.44
4/110 136 126 92.65
4/280 144 139 96.53
4/330 38 38 100.00
4/390 24 23 95.83
Availability of Specific Sun 3 Systems.
Model n Responses % Available
3/50 1486 1273 85.67
3/60 876 815 93.04
3/80 199 177 88.94
3/180 125 122 98.40
3/280 206 197 95.63
Availability of Various Systems.
Model n Responses % Available
Sun 386i 173 146 84.39
Sun 4 1583 1477 93.30
Sun 3 3960 3555 89.77
Suns 6520 5868 90.00
Vax (Rpc) 169 163 96.45
Vax 5278 3482 65.97
Sequent 33 31 93.94
Pyramid 71 60 84.51
Mean-Time-to-Repair for Sun 4 Systems.
Model n MTTR (days)
4/60 1047 1.2435
4/65 38 0.4321
4/110 136 1.1755
4/280 144 0.4963
4/390 24 0.5360
All 4s 1583 1.1259
Mean-Time-to-Repair for Sun 3 Systems.
Model n MTTR (days)
3/50 1486 3.1258
3/60 876 1.4113
3/80 199 1.8785
3/180 125 0.2155
3/280 206 0.7570
All 3s 3960 2.0209