System Uptime and Redundancy - FAQs
One of the questions we are frequently asked is: “How can I guarantee that my IT systems will never go down?” Unfortunately, there is no such thing as ‘100% Uptime’. Just ask Amazon (https://goo.gl/Ge4xzA).
This is why we often talk about system uptime in terms of ‘nines’: “three nines”, “four nines”, and “five nines”. Three nines (or 99.9% uptimes) equates to eight-hours-and-forty-five minutes of downtime over the course of one full year. Four nines (or 99.99% uptimes) equates to under fifty-three minutes of downtime over the course of one year. And five nines (99.999%) equates to five-and-a-quarter-minutes.
How do organizations achieve such uptime? One word: Redundancy. Even the best systems require periodic patching, upgrades, reboots, etc. And, that doesn’t factor in possible power outages, network connectivity disruptions, and hardware failures. Of course, we can install high-performance hardware with next-generation operating systems running on huge battery backup units, but you’re still left with periodic maintenance.
So, what is ‘redundancy’? Simply put, adding redundant systems allows for system A to be offline while system B stays up-and-running. From a service perspective: no downtime. Plus, redundancy often has the benefit of balancing the load across all active systems. Such redundancy comes in many forms:
- multiple network cards,
- multiple power supplies,
- multiple, fault-tolerant hard drives,
- multiple servers,
- multiple network appliances,
- multiple internet access paths,
- multiple geographic locations,
As you can imagine, each of these redundancy options has associated costs—with the greater uptime requiring greater expenditures. That is why every organization must decide for themselves how much downtime can be tolerated.
I hope you found this primer on redundancy helpful. As always, don’t hesitate to reach out to us with any questions.