| Five-nines reliability and what it stands for. | | | | seconds or less of downtime per year 99.99% |
| Network infrastructure providers, Telephone | | | | (Four-Nines) availability allows for 52 minutes, 36 |
| companies and Software as a Service (SaaS), as well | | | | seconds or less of downtime per year 99.9% |
| as network equipment providers claiming to offer | | | | (Three-Nines) availability allows for 8 hours, 46 minutes |
| 99.999% up-time or reliability. But how many people | | | | or less of downtime per year 99% (Two-nines) |
| actually know what it means and that a 99.999% | | | | availability allows for 3 days 15 hours and 40 minutes |
| reliability comes at a premium price. | | | | per year |
| The five-nines reliability comes originally from the | | | | In order to get more availability more reliable and |
| telecom industry. | | | | expensive equipment needs to be put in place. It |
| In a matter of fact, what is claimed as reliability is | | | | means also, buying not only the best equipment but |
| actuality availability. It means how much of the time a | | | | also the easiest to repair and building redundancy. |
| network or a piece of equipment is available for you to | | | | In addition make sure that all components have the |
| use. Availability is measured in how often something | | | | same rating. How much does it help, if your core |
| breaks and how long it takes to become available | | | | server hardware has a 99.999% reliability, but some of |
| again. A server, router or switch that crashes and is up | | | | the components in the server, like network interface |
| again within a couple of minutes falls under the | | | | cards (NIC) have only a 99% reliability. |
| five-nines reliability. | | | | It is also important to ask how much reliability is |
| Should the problem be bigger and the fix takes 15 or | | | | needed, since higher reliability will come at a premium |
| 20 minutes it wouldn't fall under the 99.999% reliability | | | | price/cost. |
| anymore but under the 99.99%. | | | | When offering service, evaluate whether your clients |
| To give you an idea what the various measurements | | | | need 99.999% reliability or maybe they can live with a |
| mean, following a few examples: | | | | 99% reliability, since you then can chose when to take |
| 99.9999% (Six-Nines) availability does only allow for 32 | | | | you network or service offline for maintenance, since |
| seconds or less of downtime per year 99.999% | | | | that is also a part that needs to be considered in your |
| (Five-Nines) availability allows for 5 minutes and 15 | | | | availability calculation. |