Six nines or 99.9999% availability

Luca Spiller
Head of Engineering
January 10, 2024

What is six nines?

Availability or uptime is typically gauged as a percentage, representing the extent of time a service operates within a designated period. Six nines availability signifies an uptime of 99.9999%, equating to downtime of less than 31 seconds per year. Striving for 100% uptime implies continuous service, accessible 24/7 without any interruptions.

What is an SLA?

Service providers usually establish service-level agreements (SLAs) that outline the expected level of service. These agreements commonly include a clause specifying the required availability, often expressed as a certain number of nines. If the provider's downtime surpasses this specified threshold, the SLA typically mandates some form of compensation to the customer, frequently in the form of a credit applicable to future services.

100% Availability Goal

The aim of any high-availability system is to reach 100% availability, but in reality, achieving this goal can be challenging. When a provider offers a Service Level Agreement (SLA), it indicates their confidence in the platform's performance and the expected level of uptime. The significance of maintaining high availability lies in the potential for substantial financial losses. Imagine the impact of a 5-minute downtime in the stock market.

How to prevent downtime?

To prevent downtime, it's essential to establish monitoring systems. WatchSumo excels at monitoring your website, detecting anomalies like increased response times that may indicate potential issues leading to downtime. In essence, WatchSumo diligently keeps an eye on your website for these signs, ensuring you receive timely alerts before any downtime occurs.

Calculating Downtime

99.9999% in a day = 0.086 seconds of downtime

99.9999% in a week = 0.6 seconds of downtime

99.9999% in a month = 2.6 seconds of downtime

99.9999% in a quarter = 7.8 seconds of downtime

99.9999% in a year = 31 seconds of downtime

Other percentiles

Six nines of uptime is just one amount, other common 'nines' are as follows: