Microsoft's cloud computing services may not have received such a blow to their reputation after all, following the news that the Sidekick data is recoverable.

Sidekick users in the US running on a T-Mobile network were thought to have lost all their contact data and content stored on their handset when Microsoft servers crashed late last week.

The disaster was said by commentators to be the biggest data loss in the history of cloud computing, and questions were asked as to why the data was not backed up in a secure place at a different location to Microsoft's main servers.

The case led to the filing of two class-action lawsuits against T-Mobile.

However, Microsoft has now said that it has recovered most, if not all, of the data, and claims that the loss was actually not as big as had been assumed.

"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," said Microsoft Premium Mobile Experiences vice president Roz Ho. "We now believe that the data loss affected a minority of Sidekick users."

Ho added that, after users get their contact details back, the rest of the data will gradually be restored, including calendar, notes, tasks, photographs and high scores.

The Sidekick data was actually stored on cloud services supplied by Microsoft subsidiary Danger, which the firm acquired last year.

Yesterday, Microsoft tried to protect its reputation by arguing that Danger's services did not run on its core cloud service technology but remained separate. But the excuse did little to calm the community's outrage.

Web users are growing to trust large tech firms because they believe that their data is backed up safely.

"We have determined that the outage was caused by a system failure that created data loss in the core database and the backup. We rebuilt the system component by component, recovering data along the way," said Ho.

"This careful process has taken a significant amount of time, but was necessary to preserve the integrity of the data."

Ho reassured Sidekick users that Microsoft had made changes to improve the overall stability of the service, and had initiated a more resilient backup process.