BlackBerry blackout: RIM breaks its silence

RIM has finally given some details about what caused a severe outage of its popular BlackBerry email service.

The company said in a statement it had ruled out security and capacity issues as a cause of the outage that left millions of so called 'CrackBerry' addicts without access to their email for several hours. The company also said the incident was not caused by any hardware failure or core software issue.

Ruling out those causes, the company has "determined that the incident was triggered by the introduction of a new, non-critical system routine that was designed to provide better optimisation of the system's cache". In computing terms, a cache is a temporary storage area that allows data to be served up quickly.

RIM said the "system routine" was not expected to impact the regular operations of the BlackBerry servers and infrastructure. But despite previous testing, the new system routine produced an unexpected impact that set off a chain reaction, triggering a series of interaction errors between the system's operational database and the cache.

After RIM isolated the database problem and tried unsuccessfully to fix the issue, it began its failover process to a back-up system. But that also failed.

The company said in the statement: "Although the back-up system and failover process had been repeatedly and successfully tested previously, the failover process did not fully perform to RIM's expectations in this situation and therefore caused further delay in restoring service and processing the resulting message queue."

RIM also said it has already identified several aspects of its testing, monitoring, and recovery processes that it plans to enhance as a result of the incident.

Since the outage began around 15:00(PDT) on Tuesday, the company had been quiet about its cause. But experts said they were convinced the issue had to do with RIM's network since subscribers were still able to make phone calls and send and receive SMS text messages.

By Wednesday morning RIM said email had begun trickling into inboxes across North America. The service was operating normally on Thursday, the company said.

Marguerite Reardon writes for CNET News.com