There are altaholics.... and then there's the rest of us. A Druid blog for the player that never wants to have to roll another character again. A Bear/Tree/Cat blog dedicated to being able to queue for all three roles in the Dungeon Finder.

Tuesday, March 9, 2010

First Post!

Partly because it's maintenance time again, and partly because I've been meaning to get writing for quite some time now, I'd like to just go through a bit of math for everyone who has ever complained about WoW's Tuesday maintenance.

Let's go ahead and take the North American servers, just for example, shall we?

Counting up the number of servers on's Realm Status page, we can see that in North America alone, there are 241 realms, total.

241 realms, not bad. A small-or-medium-sized business has 241 boxes. But these are *realms*. They aren't just one server, even though colloquially, we use the terms "realm" and "server" interchangably. No, a "realm" is Blizzard's way of saying "This is a cluster of computers, not just one." How many are there? Well, let's start with the most obvious ones: mapservers.

The mapservers are what run the world we play in. No mapserver, no Eastern Kingdoms, no Kalimdor, no Northrend, and no Outland. Those of you who have played long enough may have come across a peculiar situation, hearing the words " is down.". The way each realm works, there is one separate computer running each continent in WoW, (Technically, The Exodar, Azuremyst and Bloodmyst Isle, Silvermoon City, Eversong Woods, and Ghostland are "part" of Outland.) making it entirely possible for one part of the world to explode, while the other three continents continue chugging along.

So, 241 x 4 = 964 computers already. Let's move on.

Another server that everyone has met is the Instance server. And oh how people hate this server, because everyone hates that "Additional instances cannot be launched" message. Don't deny it, you know you hate it. It runs all the instanced content for WoW on a given realm, and you bet it gets slammed every time that new content comes out and everyone wants to get in and do stuff NOW.

241 x 5= 1205, still going.

A slightly less obvious server is the database server. This server handles all the items that exist in a given realm. And it has to track each and every item, and since we're generous, we'll assume that it also tracks each and every gold that exists as well, instead of having a different server for that as well.

241 x 6 = 1446. Now we're getting into some medium-to-large business territory.

Another slightly less obvious server is the character server, that stores all data related to your stats, your spec, your achievements, and probably your macros, glyphs, and gear sets. We'll assume that this is all run by one additional server as well.

241 x 7 = 1687.

And all of these servers have to communicate with several other shared servers as well. There's still the login server, the payment server, the account management server, the patch server, the Armory server, the Web server (checking realm status and the like) the forum server, and probably the Authenticator server as well. Again, we'll be generous and assume there is one of each, even though with an operation as large as Blizzard, there is no way in hell there is only one computer running each of these things. We're even going to ignore, for the sake of argument, the servers that run cross-server content yet, like the LFG tool, Battlegrounds, and Arena PVP. (Likely one server per Battlegroup, or a collective bunch of servers that share BG and Arena data with eachother.)

241 x 7 + 8 = 1695 servers. And maintenance is usually from 5 AM to 11 AM Pacific time. Which means that Blizzard has six hours to probably:

  • Backup the data.
  • Patch in any hotfixes.
  • Check for connectivity problems
  • Make sure that all 1695 servers are talking to each other properly, in their various capacities and amounts.
And it's not just one giant server farm, either. The North American servers are split up into four datacenters, one in Boston, one in Dallas, one in LA, and one in Seattle. You can imagine the worst tech support phonecall in the world every time that something goes wrong with two different datacenters.

This is a monumental task in and of itself. The fact that Blizzard is in fact capable of usually accomplishing all this maintenance in the allotted six-hour window should make you wonder if, in fact, they don't make regular sacrifices to Sargeras just to keep the game rolling.

In truth, we're lowballing the actual number of computers that Blizzard runs serverside. According to a graphic generated by Blizzard actually runs about 20,000 computer serverside, worldwide. Since the percentage of Wow's subscribers in North America is roughtly 22% of their total customer base, it's probably safe to say that the number of servers is closer to 4400 computers. (Here's some additional numbers from the graphic: Worldwide, Blizzard uses about 1.3 petabytes of storage, and 75,000 CPU cores.) And bear in mind, some of these numbers were released during the Burning Crusade expansion, which means that more servers, more storage, and more CPU cores are being added frequently.

So the next time that someone complains about server maintenance..... sit 'em down and show 'em some math.

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