Networking, Games, and Virtual Environments : World of Warcraft

Crashing WoW servers

John L. Miller — Wed, 30 Jul 2008 11:35:00 GMT

Yesterday I was forwarded a link about retirement of a long-time player from World of Warcraft. While that in itself might be interesting, the really juicy bit was the way he went out: with a mighty 'crash' from the server. Scalability issues, or something else?

Check out Boom's Goodbye Blog, where he describes his farewell, including the convergence of more than 1,000 players in a single capital city, and three different 40-party groups (in addition to lots of individuals) engaging in combat.

It's nice to see that WoW can scale past the 100-200 player limit (within mutual interaction range) I had privately hypothesized. It would be very interesting to find out exactly how many it could support sustained!

DVE Scalability - More to be done?

John L. Miller — Tue, 22 Jul 2008 13:53:00 GMT

Much of my last year has been spent reading about distributed virtual environment scalability. As it turns out, perhaps it shouldn't have been.

A lot of research papers I've read begins like this:

"DVE's consume loads of bandwidth, and there are lots of opportunities to improve their network usage."

Network games researchers have source access to - such as Quake III - have different behavior than the latest generation of multiplayer online games. Being an avid player of World of Warcraft, I finally spent some time analyzing traffic usage for a few basic scenarios:

Sitting in a capital city with a few hundred other players
Playing a battleground with 79 other players
Fighting in close proximity to 30+ players and several computer-controlled avatars.

I was shocked at how LOW the traffic usage was. Even when I was beating on the keyboard and mouse along with 30 other players next to each other in the battleground, my upload bandwidth stayed below 5 kbps, and download below 50 kbps. Better still, when I moved away from other players - out of interaction and viewing range - I stopped getting information about them.

There could still be issues with massively scaled games where thousands of players will be within interaction range of each other, but it's unclear if other computing resources (such as video cards) can keep up with the demand of displaying those avatars.

Does this make scalability research in DVE's obsolete? Absolutely not, but it does mean we need to be careful about what we assume is and is not already implemented.

I wonder if Blizzard talks to researchers about their Networking design...

Distributed Virtual Environment Scalability

John L. Miller — Thu, 10 Jan 2008 11:26:00 GMT

In the previous post I parrotted scalability figures for World of Warcraft. While investigating DVE's, I tripped across interesting figures for WoW and several other environments.

Halo-3

From this press release, we can see that in the first week of Halo-3's release,

2.7 million people played Halo-3 online
They logged 40 million hours of online play that week

That's absolutely astonishing for a single game! 40 million hours is 19,230 US person YEARS of work, in a week!

World of Warcraft

From Neilsen video game figures for September 2007, we see that

WoW was the most popular PC game by a factor of 3
The average player played 1051 minutes per week - 17.5 hours!

If the math holds up, that's 10 million subscribers * 17.5 hours/wk = 175 MILLION hours of WoW play per week, or 84,135 US person years of work equivalent for each week of play.

As a side note, "Traffic Analysis and Modeling for World of Warcraft" describes WoW traffic overall, and says the median download bandwidth for a player is 6.9 kbps, and the median uplink is 2.1 kbps. If we accept the peak number of simultaneous active users as 900,000, that's a total of 6.2 Gbps peak average upload from WoW datacenters for gameplay. Imagine all the processing that goes into calculating what's being communicated... Zowie!

Second Life

It's difficult to find reliable statistics for Second Life, and I haven't gone far into the research literature. From my own observations and inferences, and a quick search on the internet

Online user population tends to be between 25,000 and 50,000 at the times I connect.
A given region (a land parcel whose simulation is handled by a single server, and whose inhabitants can interact) looks able to support no more than one or two hundred users. I've seen limits of 63 attendees at invitation-only performance events, for 'technical reasons', which makes me wonder if perhaps the limit isn't 64 users per region?
Checking just now, it says 1,271,025 users have logged in in the last 60 days. Several months ago I saw a figure of 25,000 to 50,000 new accounts per day. If those numbers hold true on an average day today, and each new user logs in once, that would be 1.8M to 3M unique user logins. This leaves me uncertain of the active returning population in Second Life. Does anyone have better figures?

Anyways, enough random numbers for now. If you have anything to add, please leave a comment or send me mail, this sort of stuff is fascinating for me.

World of Warcraft hits 9M + active subscribers!

John L. Miller — Wed, 02 Jan 2008 13:06:00 GMT

The holidays gave me a chance to re-acquaint myself with World of Warcraft (WoW). I have to say, it's still the single most impressive online game I've ever seen. For my money, it does everything right. It literally *is* for my money, since I'm one of those paying 9 million subscribers.

I'm researching distributed virtual environment (DVE) scalability. As part of that, I was curious about the populations in WoW, both numbers supported per server, and total number of simultaneously active users. "A Measurement Study of Virtual Populations in Massively Multiplayer Online Games" provides a great peek into WoW, based on results from the CensusPlus UI add-in for WoW. Based on that paper, and on CensusPlus results published at http://www.warcraftrealms.com/, it appears:

There's a peak of almost 900,000 simultaneous users logged in and playing in the US and EU.
Average daily populations on a given server fluctuate by around a factor of 4-5 between minimum and maximum number of players online.
The peak number of simultaneous users on a given server appears to be around 4,000.
Data on maximum users in a zone (able to interact directly) isn't provided, but appears to be on the order of a couple hundred.

I've downloaded and added CensusPlus to my characters addins. It's out of date, but still works fine with 2.3. It's fun to see the numbers for your own server.

In summary, congratulations Blizzard on the incredibly successful World of Warcraft, and thank you researchers and add-in developers for giving us insight into player populations!