Could Skype's Own Update Have Contributed to Last Week's Outage?

BetaNews reported yesterday that Skype issued an update notice to its users for downloading the new release of its VoIP client software, on the Monday prior to what Skype engineers are now calling a "perfect storm" of events which took down its network for about 48 hours. In our report, we posed the question of how a mass Microsoft software update on Patch Tuesday have triggered such a storm on a Thursday. This morning, BetaNews' tests revealed a possible clue to an answer.

On one system last Monday, August 20, at approximately 11:00 am ET, we installed an upgrade to Skype bringing it up to version 3.5.0.214. The upgrade immediately brought up the new program, which appeared to be - and still appears to be - fully functional and in good working order. Wednesday morning, after two full system standbys (S3 sleep mode hibernation) had passed though without a full system reboot, and without the Skype client actually running, a "Restart required" message appeared on that system's screen.

The picture here is a screenshot of the actual dialog box. It's certainly nothing unusual in itself to Skype users, though what was out of the ordinary in this particular case was that it took several hours - if not days - to appear.

If similar behavior was experienced by Skype upgraders worldwide last week, it may have contributed to the "perfect storm." It may also provide a more plausible culprit for the "trigger" of that storm, as Microsoft has said its investigation turned up no evidence that its regular Patch Tuesday cycle played any contributory role in Skype's problems.

Skype's current explanation is that a bug in its P2P network resource allocation algorithm was made evident by the unusually high number of Skype client reboots this week, which reduced capacity among its supernodes for handling traffic.

The fact that Skype clients would likely have been rebooting for a reason other than their systems installing Windows updates, may also be worthy of consideration as a contributing factor. And the strange behavior we noticed today, if it's confirmed, may account for the time gap between installations (of Skype and/or Windows updates) and reboots. Skype informed BetaNews this afternoon that its engineers will be alerted to our discovery, and we may expect further comment from them as they investigate further.