Availability and reliability, measured
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
define availability and reliability with a measurement rule.
Planned topics
- Availability: share of time (or requests) the service works; reliability: how long it works without failing and how correctly.
- 99.95% monthly is about 22 minutes of allowed downtime; verify the arithmetic for your window.
- Define "up": which endpoint, which probe, which errors count, which maintenance is excluded.
- Serial dependencies multiply: two 99.9% components in series give roughly 99.8%.
- Distinguish MTTR (recovery) from MTBF (failure interval); recovery speed is often cheaper to improve.
Draft outline details
Demonstration
a table of availability targets and allowed monthly downtime, plus a measurement definition for checkout.
Check your understanding
What is missing from "we need 99.95%"?
Show answer
The measurement definition: what counts as up, where measured, over what window.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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