Microsoft and Google in a War of "Nines"

Last week, Google issued a controversial announcement, claiming that the Gmail portion of its Google Apps service had achieved 99.984 percent uptime in 2010. That's a pretty fantastical claim, especially when you consider that most Google Apps customers aren't even paying for the service. But Google took things a step further: Citing a 2010 paid study by The Radicati Group, Google also claimed that Gmail was "46 times more available than" Microsoft's Exchange Server product.

Line, meet crossed.

When Google issued this battle cry last Friday, I figured it would be best to wait until Microsoft issued a response. And now, of course, it has. According to the software giant, not only is Exchange availability comparable to that of Gmail, it's better because Microsoft measures such things more accurately. Microsoft and Google also differ significantly in their responses to customers when availability promises aren't met.

Google's original post was designed to tout the reliability of Gmail and announce some changes to Google's service level agreement (SLA) for Gmail. In 2010, for example, Google didn't count scheduled maintenance as downtime, but they will be doing so for 2011. "We are the first major cloud provider to eliminate maintenance windows from their service level agreement," the company claimed. Google is also changing the SLA to include downtimes of 10 minutes or less in the overall availability picture; that, too, wasn't the case in 2010.

But the biggest claim, of course, was Google's announced availability for Gmail in 2010: 99.984 percent, or nearly "four nines" of availability. For those not familiar with this "nines" lingo, it's a measure of availability, or uptime, or more generally of reliability. "Five nines," or 99.999, is considered "high availability," the equivalent of about six seconds of downtime a week over a year. During the server wars of the past decade, software makers raced to achieve five nines of availability in their products.

With the move to hosted services, however, the notion of achieving five nines has dropped off a bit because of the unpredictability of the Internet and the difficulty in achieving a true quality of service over external networks. But four nines (99.99 percent uptime) in a publicly hosted service is considered excellent; in real-world terms, it equates to about one minute of downtime each week for a year. For Google to have essentially achieved this level of uptime is notable. And the company says it occurred in a year in which it added "30 new features" to Gmail, and while "adding tens of millions" of new "active users."

But Google also threw a volley toward Microsoft's Exchange product line. Although it's not clear what Google meant by "Exchange"—Microsoft's messaging server is available as a standalone product for companies that want to self-host it internally, and as a hosted service from Microsoft and various third-party partners—Google did specify Microsoft's hosted version, Business Productivity Online Suite (BPOS), in part of the comparison. "Microsoft BPOS service notifications show 113 incidents in 2010: 74 unplanned outages, and 33 days with planned downtime," the Google announcement reads. "Our calculations suggest that Gmail is 32 times more reliable than the average email system, and 46 times more available than Microsoft Exchange."

Microsoft wasn't amused. And though it didn't respond to Google's claims as fully as expected, it did offer some interesting facts of its own.

First, its Exchange service in BPOS experienced 99.9 percent (three nines) or better uptime throughout 2010, the company says. This is in line with its SLA-based commitment to customers. But Microsoft took offense to Google's redefining of what is and is not counted toward the uptime figure: "Any service issue \[is counted\] as downtime, from the minute it starts to resolution," a Microsoft representative wrote via email, discrediting Google's claims.  "We also count issues for any number of impacted users, not just if 'enough' users are impacted." The claim being that Google simply discounts downtime issues if they affect only a portion of its users. Microsoft, by contrast, counts all downtime.

Microsoft and Google also differ in the way they respond to paying customers who don't receive the uptime guaranteed by each company's SLA. (Both Microsoft and Google promise 99.9 percent uptime. Google has both free and paid Google Apps customers and only fully supports paid customers.) Google extends the subscription time for affected customers by the amount of time they lost. But Microsoft offers cash reimbursements.

Long story short, Google is almost certainly overstating its uptime figures for Gmail on Google Apps. It is also bringing its uptime calculations for 2011 more in line with what Microsoft was already doing. And finally, Microsoft's real-world uptime for its BPOS-based Exchange service is almost certainly at or above that of Gmail.

That said, Google does offer some notable advantages over Microsoft. Millions of Google customers are using a free version of Gmail and/or Google Apps, and Microsoft doesn't have a comparable free offering. And when comparing the paid version of Google Apps with BPOS (or, in the future, Office 365, which will lower prices and consolidate BPOS and other services under a brand umbrella), the Google offering is still cheaper.

All this said, I'm surprised that Microsoft hasn't issued a more detailed response to Google. Maybe that's still coming.