Appendix B. Availability Chart
As mentioned in Chapter 4, Table B-1 is a chart of availability numbers. Itâs a great reference for how much downtime is allowed within a given availability target.
Availability % | Downtime per year | Downtime per month | Downtime per week | Downtime per day |
---|---|---|---|---|
90% (âone nineâ) |
36.5 days |
72 hours |
16.8 hours |
2.4 hours |
95% (âone and a half ninesâ) |
18.25 days |
36 hours |
8.4 hours |
1.2 hours |
97% |
10.96 days |
21.6 hours |
5.04 hours |
43.2 minutes |
98% |
7.30 days |
14.4 hours |
3.36 hours |
28.8 minutes |
99% (âtwo ninesâ) |
3.65 days |
7.20 hours |
1.68 hours |
14.4 minutes |
99.5% (âtwo and a half ninesâ) |
1.83 days |
3.60 hours |
50.4 minutes |
7.2 minutes |
99.8% |
17.52 hours |
86.23 minutes |
20.16 minutes |
2.88 minutes |
99.9% (âthree ninesâ) |
8.76 hours |
43.8 minutes |
10.1 minutes |
1.44 minutes |
99.95% (âthree and a half ninesâ) |
4.38 hours |
21.56 minutes |
5.04 minutes |
43.2 seconds |
99.99% (âfour ninesâ) |
52.56 minutes |
4.38 minutes |
1.01 minutes |
8.64 seconds |
99.995% (âfour and a half ninesâ) |
26.28 minutes |
2.16 minutes |
30.24 seconds |
4.32 seconds |
99.999% (âfive ninesâ) |
5.26 minutes |
25.9 seconds |
6.05 seconds |
864.3 milliseconds |
99.9999% (âsix ninesâ) |
31.5 seconds |
2.59 seconds |
604.8 milliseconds |
86.4 milliseconds |
99.99999% (âseven ninesâ) |
3.15 seconds |
262.97 milliseconds |
60.48 milliseconds |
8.64 milliseconds |
99.999999% (âeight ninesâ) |
315.569 milliseconds |
26.297 milliseconds |
6.048 ... |
Get Practical Monitoring now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.