Availability Table

URL: https://sre.google/sre-book/availability-table/
Author: sre.google

Summary

The availability of a service is measured by how long it is unavailable over time. A table shows the allowed downtime for different availability levels, ranging from 90% to 99.999%. For services with partial availability, it's better to use an aggregate unavailability metric instead of just outage lengths.

Highlights added August 30, 2024 at 2:23 PM

Availability level Allowed unavailability window
per year
per quarter
per month
per week
per day
per hour
90%
36.5 days
9 days
3 days
16.8 hours
2.4 hours
6 minutes
95%
18.25 days
4.5 days
1.5 days
8.4 hours
1.2 hours
3 minutes
99%
3.65 days
21.6 hours
7.2 hours
1.68 hours
14.4 minutes
36 seconds
99.5%
1.83 days
10.8 hours
3.6 hours
50.4 minutes
7.20 minutes
18 seconds
99.9%
8.76 hours
2.16 hours
43.2 minutes
10.1 minutes
1.44 minutes
3.6 seconds
99.95%
4.38 hours
1.08 hours
21.6 minutes
5.04 minutes
43.2 seconds
1.8 seconds
99.99%
52.6 minutes
12.96 minutes
4.32 minutes
60.5 seconds
8.64 seconds
0.36 seconds
99.999%
5.26 minutes
1.30 minutes
25.9 seconds
6.05 seconds
0.87 seconds
0.04 seconds ([View Highlight] (https://read.readwise.io/read/01j3y5rdykd36exyw23b3wra45))