One of the fun things about interviewing is the times you wind up geeking out about tech or business with a simpatico interviewer. I have been talking to a good number of such people this week, and one of the conversations I keep having is the one about using virtual servers in the cloud to handle MMO launch loads. This is a really good strategy for anything Web-based. Zynga used to launch and host new games on Amazon’s EC2, although they’ve pulled back on EC2 usage because it’s cheaper to run enough servers for baseline usage in their own data centers. There are, likewise, a ton of Web startups using EC2 or any of the other public clouds to minimize capital expenditure going into the launch of a new product.
Not surprisingly, people tend to wonder about using the same strategy for an MMO. Launch week for any MMO is a high demand time, so why not push the load into the cloud instead of buying too much hardware or stressing out the servers?
It’s an uptime problem. I don’t worry too much about the big outages — those are fluke occurrences and your datacenter’s network could have a problem of similar severity on your launch day. I do worry about the general uptime.
Web services are non-persistent. (Mostly. Yes, SPDY changes that.) A browser makes an HTTP request, and then can safely give up on the TCP connection to the Web server. State doesn’t live on individual Web servers, so if Web server one dies before the next HTTP request, you just feed the next request to Web server two and everyone’s happy.
MMO servers are persistent. (Mostly. I’m sure there are exceptions, which I would love to hear about.) The state of a given instance or zone is typically maintained on an instance/zone server. If that server dies, most likely the people in that instance are either kicked off the game or booted back to a different area. This is lousy MMO customer experience.
So that’s why I don’t think in terms of cloud for MMO launches. That said, I don’t think these are inherent problems with the concepts. Clouds can be more stable, and Amazon’s certainly working in that direction. For that matter, there are other cloud providers. Likewise, I can sketch out a couple of ways to avoid the persistence problem. I’m not entirely sure they’d work, but there are possibilities. You can at the least minimize the bad effects of random server crashes.
Still and all, it’s a lot trickier than launching anything Web-related in a public cloud.