five nines calculation in uptime monitoring


FYI: FREE SERVER UPTIME MONITOR AND ALERT SERVICE - BASICSTATE.COM

Buyers and sellers of web hosting services talk a lot about 5 9's uptime. Users often forget about the effect of the decimal place in a percentage representation in calculating allowable downtime for a particular service level agreement.

For example, since 1 percent is another way of expressing .01, then when speaking of five nine's uptime, or 99.999 percent uptime, then the related downtime calculation factor is not 0.001, but 0.01 of 0.001, or 0.00001, two more decimal places to the right.

The values have been precalculated in the following tables for yearly, monthly, and daily downtime totals for a range of values. This will help readers of the free server uptime reports from basicstate.com relate the percentage level of uptime shown in the report with actual downtime budgets. The global daily uptime digest reports can be compared against these five nines numbers. New users can register for a free account here.

            

uptime year month day days hh:mm:ss days hh:mm:ss hh:mm:ss
99.9990 0 00:05:15 0 00:00:27 00:00:01 99.9900 0 00:52:34 0 00:04:28 00:00:09 99.9000 0 08:45:36 0 00:44:38 00:01:26 99.0000 3 15:36:00 0 07:26:24 00:14:24
98.0000 7 07:12:00 0 14:52:48 00:28:48 97.0000 10 22:48:00 0 22:19:12 00:43:12 96.0000 14 14:24:00 1 05:45:36 00:57:36 95.0000 18 06:00:00 1 13:12:00 01:12:00 94.0000 21 21:36:00 1 20:38:24 01:26:24 93.0000 25 13:12:00 2 04:04:48 01:40:48 92.0000 29 04:48:00 2 11:31:12 01:55:12 91.0000 32 20:24:00 2 18:57:36 02:09:36 90.0000 36 12:00:00 3 02:24:00 02:24:00

An explanation of how two 99.9 percent available load balanced hosts achieve 99.99 percent uptime .

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source: basicstate.com