Google has announced that it has made some changes to its service level agreement (SLA) for Google Apps, to reduce the possibility that users will experience any downtime. The company says it has eliminated maintenance windows from the SLA, so Google will never plan for users to be down when they’re upgrading services or maintaining their systems. 

"People expect email to be as reliable as their phone’s dial tone, and our goal is to deliver that kind of always-on availability with our applications," says Matthew Glotzbach, Google’s Enterprise Product Management Director. "Going forward, all downtime will be counted and applied towards the customer’s SLA."

Google has also made changes to the SLA so that any intermittent downtime is counted. "Previously, a period of less than ten minutes was not included," explains Glotzbach. "We believe any instance that causes our users to experience downtime should be avoided — period."

According to Google, Gmail was available 99.984% of the time in 2010 for both businesses and consumers, which works out to about 7 minutes of downtime per month on average. Glotzbach says this represents the accumulation of small delays of a few seconds. 

"Seven minutes of downtime compares very favorably with on-premises email, which is subject to much higher rates of interruption that hurt employee productivity," he says, providing the following graph:

As you may know, Microsoft’s Hotmail recently experienced some issues, which led to our conversation about users’ dependency and vulnerability when it comes to using web services- particularly for email.

At the end of December, some Hotmail users lost messages and folders from their accounts temporarily. On January 6, Microsoft explained what happened, and said it had all been recovered, though for those who didn’t sign into their accounts between the time of the incident and the time the account was restored, any messages sent to their accounts during that time would have bounced.  

While I’d be interested to see another chart like the one above, comparing Gmail with other webmail providers like Microsoft’s Hotmail, Yahoo Mail, etc., Gmail’s case is looking pretty good compared to the on-premises email.