In an effort to explain to the world what happened on the August 16th, Villu Arak had a second go at explaining: The Microsoft Connection Clarified. Unfortunately, many saw the first explanation from yesterday to be a stab at Microsoft:
“The disruption was triggered by a massive restart of our users’ computers across the globe within a very short timeframe as they re-booted after receiving a routine set of patches through Windows Update.”
In today’s posting, one of the first things Arak covered was that Skype was not blaming Microsoft for the outage:
“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 self-healing mechanisms of the P2P network upon which Skype’s software runs have worked well in the past….
…Unfortunately, this time, for the first time, Skype was unable to rise to the challenge and the reasons for this were exceptional. In this instance, the day’s Skype traffic patterns, combined with the large number of reboots, revealed a previously unseen fault in the P2P network resource allocation algorithm Skype used. Consequently, the P2P network’s self-healing function didn’t work quickly enough.”
Previously updates and patches from MS didn’t cause the same problem because there were other elements involved this time:
“In previous instances where a large number of supernodes in the P2P network were rebooted, other factors of a “perfect storm†had not been present. That is, there had not been such a combination of high usage load during supernode rebooting.”
Can we expect things like this to happen again in the future?
“Yes, the bug has been squashed. The parameters of the P2P network have been tuned to be smarter about how similar situations should be handled. Once we found the algorithmic fix to ensure continued operation in the face of high numbers of client reboots, the efforts focused squarely on stabilising the P2P core. The fix means that we’ve tuned Skype’s P2P core so that it can cope with simultaneous P2P network load and core size changes similar to those that occurred on August 16. We’d like to reassure our users across the globe that we’ve done everything we need to do to make sure this doesn’t happen again. We’ve already introduced a number of improvements to our software to ensure our users will not be similarly affected – in the unlikely possibility of this combination of events recurring.”
