5 9 Availability: What Does It Really Mean?

2021.07.09

The availability of five 9s (i.e. 99.999%) is the percentage of time a user can access a network component or service over a given period of time (usually defined as a year). The migration from proprietary networks to cloud services enables enterprises to require service providers to provide five 9s of availability. It is critical that businesses continue to add more mission-critical applications and services that must be highly available and keep downtime to a minimum. When resources are inaccessible, employees, customers, and supply chain partners no longer have access to the information or services they need.  

5 9s and other percentages of availability  

Although the goal is 100% availability, it is not reasonable to expect to use the service every minute of every day throughout the year. Maintenance, upgrades, and uncontrollable events (or force majeure) prevent suppliers from guaranteeing 100% uptime. 5 9 Availability Service Level Agreements (SLAs) are demanding; It requires that a given service be unavailable for no more than 5 minutes and 15 seconds per year. The service availability covered by the SLA is 4 9s (i.e. 99.99%), and may be unavailable for 52 minutes and 36 seconds per year. The availability of the three 9s (99.9%) allows for 8 hours and 46 minutes of downtime per year. Maintaining the five 9 service availability percentages requires significant investment and maintenance, using established network configurations, monitoring, and troubleshooting network issues, and following best practices to ensure that system components remain up and running. The inability of a service to be unavailable per hour can cost the company millions of dollars. 

5 9 availability

How do I get more 9? Consider the following steps:
Buy the best equipment that's easiest to repair. Then, add load balancing, failover, and redundancy. Highly available systems typically include power supplies and processors, backup batteries, diesel or natural gas generators (for longer blackouts than batteries can handle), multiple different communication lines, and any other equipment that may fail .
Where possible, automatically monitor network performance and flag potential failures. Automation tools, network analytics software that continuously tracks the health of network components, and technologies such as artificial intelligence and machine learning can help operators reduce the chance of human error and keep their networks up and running. In addition, artificial intelligence and machine learning platforms proactively alert network operators in the event of network problems or security vulnerabilities and automatically transfer operations from failed components to backups if necessary.
Pay attention to the software. Outdated or unpatched software may make the availability of 5 9s impossible. Availability is affected if a particular component fails due to an operating system failure and takes a long time to return to the online system.
Test backup and disaster recovery plans to ensure they are adequate for disaster incidents.