Data from T-Mobile Sidekicks has been mostly recovered, according to Microsoft.
Last week, a glitch deleted data held on Microsoft subsidiary Danger's servers for US T-Mobile Sidekick users. The failure was seen as evidence by many that cloud computing wasn't entirely secure.
Roz Ho, corporate vice president for premium mobile experiences at Microsoft, said "most, if not all, customer data" had been recovered, and that the fault affected "a minority of Sidekick customers."
"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," she added. "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."
She promised the next update on data restoration would be posted by Saturday at the latest.
Microsoft attributed the problem to a database error. "We have determined that the outage was caused by a system failure that created data loss in the core database and the back-up," Ho said. "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."
Apologising for the fault, Ho promised Microsoft had taken "immediate steps" to ensure it won't be repeated.
"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," she explained.
