If you’ve been following the tech news lately, you’ve probably heard at least a bit about the massive blackberry outage over the past three days. While yes, it’s the first truly grand failure of RIM’s infrastructure in their 12-year history, it’s also a wonderful case study.
Apparently the outage started Monday morning with RIM infrastructure in Europe, the Middle East and Asia. However, by Wednesday, it had become a global outage/slowdown of BlackBerry infrastructure (specifically the parts that go through RIM - email, web browsing, and BBM; voice calls and SMS/MMS were unaffected). With BlackBerry’s market share falling, Android’s rapidly growing (and Android slowly becoming a viable enterprise option), and the launch of the iPhone 4S just around the corner, the timing of this couldn’t be worse for RIM.
RIM’s original statement about the problem, at 21:30 on Tuesday October 11th, was,
The messaging and browsing delays that some of you are still experiencing were caused by a core switch failure within RIM’s infrastructure. Although the system is designed to failover to a back-up switch, the failover did not function as previously tested. As a result, a large backlog of data was generated and we are now working to clear that backlog and restore normal service as quickly as possible. We sincerely apologise for the inconvenience caused to many of you and we will continue to keep you informed.
I haven’t been able to find much more technical information than that - a CNET article from Tuesday goes into as much depth as anything I could find. I did find one mention (misplaced the link) that the core switch in question uses technology from “multiple vendors”. So what follows is part common sense (for me… why not for a multi-national corporation?) and part speculation. If you’re unfamiliar with RIM’s architecture, the pertinent points are that all Internet-bound traffic (browsing, email, and BBM) is piped through RIM’s data centers, where it’s encypted and who-knows-what-else’ed (perhaps monitored) before going back out onto the ‘net. In the Enterprise market, their big claim is encryption/security, and monitoring/management/policy enforcement on handsets.
First main point: RIM is a big company. The thought that they rely on an (apparently custom) core switch - a single core switch for multiple continents - is amazing. It’s even more amazing that they’d let such a large part of their infrastructure ride on an architecture with, apparently, an untested failover mechanism. Of course I don’t know all the details, but I’d hope that for a single piece of hardware which is so critical, they’d a) have a cold spare physically nearby so a replacement wouldn’t take a day or two, and b) if they can’t do an online failover test, at least have a full lab environment to test the failover in.
Second main point: Their big claim through all of this is that they didn’t lose any data - email, BBM, etc. - it just got delayed. So if there was a core switch failure in their data center serving EMEA, and the next day global services slowed to a crawl, the only thing that comes to mind to me is a waterfall; EMEA went down, and they started rerouting traffic to their North America data center. The increased load - probably a disaster recovery plan they never truly tested or even planned - brought everything to a screeching halt, and caused them to resort to simply caching messaging and pushing it out bit by bit as the infrastructure could handle. Oops.
So what are my (admittedly poorly-informed) thoughts on this?
Scaling out works. Scaling up - especially with single points of failure, or N+1 redundancy - is dangerous. If RIM had scaled out and used regional data centers, with a close-to-commodity core and as much redundancy as possible, this wouldn’t have happened. Sure, infrastructure costs money. But if that one “core switch” had been 1,000 devices spread across multiple racks in multiple data centers, this never would have happened. And the devices would be comparatively cheap enough to probably keep spares on hand too. And regularly test their failover procedures. To all of the big businesses (apparently like RIM) who still think that big iron is the only way to do things right… maybe it’s time to take a hard look at that, and compare your architecture to that of the modern, new, hip giants like Google and Facebook. Grids and clusters. Nodes that can fail without anyone blinking. Scaling out might not fix every problem, but having half the world on a single core switch with N+1 redundancy probably isn’t smart either.
Disasters need to be planned for. Every possible contingency needs to be planned for. Plans need to be tested, regularly. If your giant core switch goes down and the failover doesn’t “function as previously tested”, there’s a serious problem both in your disaster planning, and in your validation and test procedure. If you have half of your customer base riding on a failover plan that isn’t regularly tested or otherwise validated, that’s bad. While I can argue that the whole architecture - given this massive point of failure - could stand to be re-thought, the real issue here is with test/validation methodologies and procedures. For a company with 70 million users, having a piece of infrastructure this critical fail, and the failover ‘not work as tested’ is a very serious issue.
Damage control is important. As I said, I can only imagine that the severe service degradation outside of EMEA was due to rerouting data from EMEA to the remaining functional data center(s). Such a solution should only be considered if it has been tested, or at least has engineering validation. If it was part of the disaster recovery plan, it obviously isn’t actually a suitable solution, and served only to increase the scope of the outage. If it wasn’t part of the disaster recovery plan, and was decided on-the-fly, someone really didn’t do their research and engineering before putting the fix in place. A workable solution should have been planned ahead of time. And if one wasn’t, it’s very bad practice - this outage shows the results - to put in place a fix that hasn’t been thought out.
For a company whose business is so telecom-focused, this seems like a glaringly bad design that shouldn’t be acceptable in a telecom.