Skype: Microsoft patches didn't spark our outage

Skype offered up some more details about its two-day outage last week and noted that Microsoft patches were not to blame.

This point was fairly clear in its initial blog posting on the incident. Microsoft's Windows update was a catalyst not the reason for the outage.

Skype said Tuesday (see Techmeme for more):

We don’t blame anyone but ourselves. The Microsoft Update patches were merely a catalyst — a trigger — for a series of events that led to the disruption of Skype, not the root cause of it. And Microsoft has been very helpful and supportive throughout.

The high number of post-update reboots affected Skype’s network resources. This caused a flood of log-in requests, which, combined with the lack of peer-to-peer network resources at the time, prompted a chain reaction that had a critical impact. The self-healing mechanisms of the P2P network upon which Skype’s software runs have worked well in the past. Simply put, every single time Skype has needed to recover from reboots that naturally accompany a routine Windows Update, there hasn’t been a problem.

Unfortunately, this time, for the first time, Skype was unable to rise to the challenge and the reasons for this were exceptional.

So what was different this time around with the patches.

Skype said nothing was different.

In short – there was nothing different about this set of Microsoft patches. During a joint call soon after problems were detected, Skype and Microsoft engineers went through the list of patches that had been pushed out. We ruled each one out as a possible cause for Skype’s problems. We also walked through the standard Windows Update process to understand it better and to ensure that nothing in the process had changed from the past (and nothing had).

More importantly Skype said it has squashed the bug that led to the outage. As for the lessons learned they still apply for Skype.