Microsoft: The Sidekick Data is Back

Following several days of hints and rumors, Microsoft has confirmed that it has resurrected most of the Sidekick user data that was believed to be lost. The announcement marks a major turnaround in a story that has prompted widespread discussion about the reliability of cloud data storage. Microsoft says it now believes the data loss "affected a minority of Sidekick users."

"We are pleased to report that we have recovered most, if not all, customer data for those Sidekick customers whose data was affected by the recent outage," said Roz Ho, Microsoft's Corporate Vice President for Premium Mobile Experiences. "We plan to begin restoring users’ personal data as soon as possible, starting with personal contacts, after we have validated the data and our restoration plan. We will then continue to work around the clock to restore data to all affected users, including calendar, notes, tasks, photographs and high scores, as quickly as possible."

The recovery helps save face for Microsoft, but some analysts say that while Sidekick users will welcome the restoration of their contacts, many have already shifted their attention to other mobile devices and services.

Last week T-Mobile told users of its popular Sidekick mobile that all of their data had been lost, blaming a server failure at Microsoft’s Danger subsidiary and saying "the likelihood of a successful outcome is extremely low."

How did the failure happen? Details remain sketchy, and Microsoft's statement is vague. "We have determined that the outage was caused by a system failure that created data loss in the core database and the back-up," said Ho. "We rebuilt the system component by component, recovering data along the way. This careful process has taken a significant amount of time, but was necessary to preserve the integrity of the data."

Microsoft’s statements this week have not addressed how both the primary and backup databases could be affected by the same event – a possibility most backup systems are designed to avert. But Microsoft confirmed that the Sidekick data was housed at Danger, a software company Microsoft bought in 2008, rather than any of Microsoft’s enormous cloud computing centers.

“The Sidekick runs on Danger’s proprietary service that Microsoft inherited when it acquired Danger in 2008,” Microsoft said. “The Danger service is built on a mix of Danger created technologies and 3rd party technologies. Microsoft’s other cloud computing projects are totally separate from the Danger Service and do not rely on the Danger Service technology.”

In today's statement, Ho said Microsoft was "taking immediate steps to help ensure this does not happen again. Specifically, we have made changes to improve the overall stability of the Sidekick service and initiated a more resilient backup process to ensure that the integrity of our database backups is maintained."