Microsoft launchedabout two years ago with the promise of high availability. And, really, in a fast-paced business world, anything but high availability is a failure. Microsoft does many things to ensure high availability of Office 365, including providing a financially backed service level agreement (SLA) for a guaranteed uptime of 99.9 percent. Today, in a blog post on the Office 365 site, Microsoft has provided its quarterly uptime numbers for the span of July 2012 to June 2013. For the quarters between this time period, Office 365 has seen 99.98 percent, 99.97 percent, 99.94 percent, and 99.97 percent uptime, respectively.
In the future, Microsoft is promising to display each quarter's uptime numbers on the Office 365 Trust Center website. The Office 365 Trust Center is a billboard for Microsoft to ensure that its privacy, trust, transparency, security, and continuity message is loud and clear. This is an extremely important focus for the company due to recent reports that PRISM is eating into the Microsoft Cloud revenue potential.
The numbers presented today are based on the various Office 365 components, the number of people using them, and the average uptime. For example, individual customers might have had different experiences, but the overall average is used in the calculation. Also, the stats are based on Office 365 for business, education, and government, and do not include the consumer side or Office 365 ProPlus (which is primarily a device-side application).
In the blog post, Microsoft goes further into how it's able to achieve its stellar uptime numbers using techniques such as redundancy, resiliency, distributed services, monitoring, simplification, and even humans.
You can dig into the specifics for each of these techniques at the source: Cloud services you can trust: Office 365 availability