What Is Uptime?
“Uptime” defines the percentage of time a particular system is operational. In IT, it is one of the most vital metrics associated with the performance of mission-critical systems. The higher the uptime, the more available and better-performing the system. A lower uptime indicates a less reliable system with greater potential for downtime. Because it is such an impactful metric, IT teams pay close attention to uptime when evaluating their own networks and considering service providers.
Uptime and SLAs
As a result, many data centers and providers of cloud, data and network services include uptime in the section of their service contracts called a service-level agreement (SLA). This agreement formally defines the level of uptime the company can expect from the provider, often including metrics for the percentage of network uptime, power uptime and number of scheduled maintenance windows.
The Significance of “Nines”
In service provider SLAs, uptime is traditionally measured in nines — the more nines, the better the uptime. The number of nines also correlates to an expected amount of downtime over a given period.
Uptime SLA Table
| Downtime/ Year | Downtime/ Month | Downtime/ Week | Downtime/ Day | Uptime |
|---|---|---|---|---|
| 3.65 days | 7.20 hours | 1.68 hours | 14.4 minutes | 99% (“two nines”) |
| 8.76 hours | 43.8 minutes | 10.1 minutes | 1.44 minutes | 99.9% (“three nines”) |
| 52.56 minutes | 4.38 minutes | 1.01 minutes | 8.64 seconds | 99.99% (“four nines”) |
| 5.26 minutes | 25.9 seconds | 6.05 seconds | 864.3 ms | 99.999% (“five nines”) |
| 31.5 seconds | 2.59 seconds | 604.8 ms | 86.4 ms | 99.9999% (“six nines”) |
| 3.15 seconds | 262.97 ms | 60.48 ms | 8.64 ms | 99.99999% (“seven nines”) |
| 315.569 ms | 26.297 ms | 6.048 ms | 0.864 ms | 99.999999% (“eight nines”) |
| 31.5569 ms | 2.6297 ms | 0.6048 ms | 0.0864 ms | 99.9999999% (“nine nines”) |
What “Five Nines” Actually Means
Five nines, or 99.999%, is a highly valued level of system availability often recommended for mission-critical applications and in performance-sensitive industries like finance and ecommerce. Achieving this level of uptime is difficult, especially in environments like data centers where there are numerous factors that can affect operations. That’s why it is important for companies to make the right considerations when evaluating their off-site data centers as well as their other service providers.
How to Improve Uptime
While many service providers seek to improve their uptime, most companies are looking for ways to leverage higher uptime. This is often easier said than done given the number of competing cloud, data and network providers on the market today, which is why it’s important for businesses to define the performance requirements for their mission-critical systems and end-users so they can make smarter decisions on service providers.
If you’re interested taking advantage of better uptime for your mission-critical systems, give us a call at NEF to explore your options.