Five Nines: What it means, how to achieve it, and whether it is right for your needs
4 min read
One of today’s buzziest trends in cloud computing is the idea of “five nines”—when a network is up 99.999 percent of the time. In an ideal world, all networks would enjoy 100 percent uptime, but in reality, that’s just not feasible. Instead, businesses can attempt to configure their networks to get as close as best fits their needs.
Reaching five nines is a complex endeavor, and as such, businesses should be prepared to commit a substantial amount of both resources and time towards obtaining this degree of performance.
What is five nines?
When a network is described as having “five nines” uptime, it means that it operates at 99.999 percent availability. In practical terms, this translates to a permitted 5.26 minutes of downtime per non-leap year. On a monthly basis, that’s just 25.9 seconds down.
Unlike many industry-specific performance guarantees, five nines isn’t regulated by any official overseeing body. It’s far more common to see “five nines” touted in a colocation facility’s marketing materials than cited by a system engineer with regard to their work. Since it’s an unregulated term, be prepared for a fair amount of ambiguity in how providers chose to define five nines. For example, many will exempt scheduled maintenance from the overall calculation used to determine uptime percentage.
How to achieve five nines?
Securing five nines is not easy. The difference in cost between 99 percent uptime, or 3.65 days down per year, and 99.999 percent can be staggering, especially for smaller or medium-sized businesses.
The primary driver behind the cost increase is the requirement for redundancy. Even Tier 4 data centers offer 99.995 percent availability at best. Five nines relies on multiple data centers operating simultaneously, so that if one fails, others will pick up the slack. It’s less about having one ultra-optimized facility and much more about establishing a model for redundancy that encompasses an entire network.
Be sure to obtain guarantees from service providers with regard to minimum notice periods before planned downtime. Additionally, determine countermeasures in advance for when scheduled maintenance continues for longer than is initially expected. The key to true 99.999 percent uptime is in the creation of an appropriate architecture that can deliver even when things don’t go according to plan.
Does my business need five nines?
Five nines, while advantageous, isn’t always a must-have. Globe-spanning conglomerates with round-the-clock user activity may decide that nothing less than 99.999 percent is acceptable, but most companies aren’t operating at that scale. Many businesses considering five nines will want to focus on those times when users are most active.
Consider a SaaS platform primarily serving the US. It’s not likely that this business would view five nines as mandatory for other regions. Even though this company’s market spans four time zones, there’s still plenty of time during which the vast majority of its users will be inactive. It’s during these windows of low activity that maintenance, system scans and system backups should be scheduled.
Outages in peak usage hours can incur severe . In addition to lost revenues, companies also suffer damages to both productivity and reputation. Even if an application can’t be fully disabled, service providers can compensate by utilizing a scale-up and scale-down approach to strategically take servers offline when needed.
Slide down an order of magnitude to four nines, or 99.99 percent availability, and networks are allowed up to 52.56 minutes of downtime per year. Depending on one’s industry and scope of business, this difference might be significant, or it might be negligible. Businesses interested in five nines should assess whether the advantages of those extra 50 minutes of yearly uptime are worth the effort and cost needed to get there.
Five nines: an attainable goal with a weighty investment.
Five nines performance is advisable for mission-critical processes with a sustained population of active users, but it’s much less necessary outside of this specific circumstance. And because achieving five nines is such an involved and expensive process, it’s naturally not going to be something everyone will want to pursue.
Businesses desiring five nines should construct redundant ecosystems out of highly available components, including their data centers and network stacks. Architecting and designing one is often as costly as it is complex. Selecting a data center is all about matching the capabilities of the facility to the needs of the business, and a single facility is only one factor in a holistic five-nines infrastructure.