<h1 id="nines-of-reliability">Nines of Reliability<a aria-hidden="true" class="anchor-heading icon-link" href="#nines-of-reliability"></a></h1>
<p>"Nines of reliability" are often used to discuss availability constraints for a system.</p>
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<table><thead><tr><th>Uptime percentage</th><th>Downtime in 28 days</th></tr></thead><tbody><tr><td>99.9%</td><td>40 minutes</td></tr><tr><td>99.99%</td><td>4 minutes</td></tr><tr><td>99.999%</td><td>24 seconds</td></tr></tbody></table></div>
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<strong>Backlinks</strong>
<ul>
<li><a href="/notes/3bd1ae8f-d39b-4707-8341-bc8fd29ebbb7">Site Reliability Engineering (public)</a></li>
<li><a href="/notes/70dc889b-d16a-49e7-a8f6-210a9be197a7">Service Availability Calculus (public)</a></li>
<li><a title="Private" href="https://wiki.dendron.so/notes/hfyvYGJZQiUwQaaxQO27q.html" target="_blank" class="private">01: The "Success" in SRE is Silent (internal) (Private)</a></li>
</ul>

Nines of Reliability


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Hi, I'm Luke 👋

I'm a software engineer turned site reliability engineer. I'm currently big on knowledge management and learning.

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Uptime percentage	Downtime in 28 days
99.9%	40 minutes
99.99%	4 minutes
99.999%	24 seconds