T-Mobile customers in the US who use the Sidekick handset have been told they almost certainly have no chance of recovering personal data lost last week in a service breakdown.
The affected data includes contacts, calendar entries, to-do lists and photos. The data was held on servers by Danger, which was acquired by Microsoft last year. The Sidekick is T-Mobile's name for Danger's 'Hiptop' device, and the service for the device is supplied by the Microsoft subsidiary.
According to an update issued on Saturday by T-Mobile and Microsoft on T-Mobile US's forums, the affected data has "almost certainly been lost as a result of server failure at Microsoft/Danger".
"That said, our teams continue to work around-the-clock in hopes of discovering some way to recover this information," the update read. "However, the likelihood of a successful outcome is extremely low."
Danger's approach is to provide much of its handsets' functionality — from the camera to instant messaging — as hosted services, with the handset itself holding little more than a cached version of what was most recently synchronised to it. Sidekick customers' data was being hosted in Microsoft datacentres at the time of the crash on Tuesday.
T-Mobile US and Microsoft said they will issue a further update on Monday to give details on "the status of the remaining issues caused by the service disruption, including the data-recovery efforts and the Download Catalog restoration which we are continuing to resolve".
Apologising for the data loss, the companies warned users not to reset their Sidekicks or let the battery drain, otherwise any remaining data on the handsets could be lost.
Telecoms analyst Dean Bubley, of Disruptive Analysis, said on Monday that it was difficult to judge the direct implications for Microsoft's trustworthiness in protecting users' data without knowing how far the integration process between Microsoft's and Danger's systems had gone.
"Interestingly, what that may imply is that, while there may well be cloud-computing growth, perhaps the fragility around it is where customers grow by acquisitions rather than organic growth," Bubley said. "Acquisitions are notoriously difficult to integrate."
Bubley also questioned the use of a cloud-based service for managing the personal information of handset users. "Memory is so cheap that I can't see any argument for not having a local backup on the handset," he said. "Unless it's high-resolution video, the only reason to not have local backup is if companies are trying to enforce lock-in."