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Revised 2022-08-02T10:23:14Z

You are often presented with tables describing the availability (uptime) for different resources. The opposite value would be the unavailability (downtime).

I really think that it would be better to show downtime instead of uptime, since it is easier to comprehend for most of us. Compare 99.9917% to 0.0083%.

Another benefit is that you can skip to show the 0% values, which will be understandable and natural, while skipping the 100% values may not be.

I would argue that the values in the downtime column in the table below, is much, much easier to get a grip of than the values in the uptime column. You can easily understand the magnitude of the values in the downtime column, while you probably need to make an implicit subtraction for each value when looking in the uptime column.

Resource Uptime % Downtime %
First server 99.9993 0.0007
Second server 100.0000
Third server 99.9984 0.0016
Fourth server 99.9812 0.0188
Fifth server 100.0000
Sixth server 99.9999 0.0001
Seventh server 99.9975 0.0025
Eighth server 99.8743 0.1257
Ninth server 98.9999 1.0001

Another thing when using uptime value is that the uptime values are probably (always?) converted to downtime values, to understand the actual number of seconds/hours/days a resource is down (unavailable).

When displaying downtime, you can also make the table even more readable, by skipping useless zeroes:

Resource Uptime % Downtime % (10-4)
First server 99.9993 7
Second server 100.0000
Third server 99.9984 16
Fourth server 99.9812 188
Fifth server 100.0000
Sixth server 99.9999 1
Seventh server 99.9975 25
Eighth server 99.8743 1257
Ninth server 98.9999 10001

Conclusions

So my recommendation is to always present downtime values instead of uptime values.

First published by Anders Gustafson 2022-06-05.
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