WoW: Forever launch used 70,480 CPU cores and 251 terabytes of RAM

Blizzard pulled out all the stops to ensure World of Warcraft: Forever survived a chaotic launch night. What was the company's secret weapon? Splurging an absurd amount of money on infrastructure made up of 3,924 virtual machines with 70,480 CPU cores and a whopping 251,136 GB, or 251 TB, of memory.

Praised by media and players as one of the smoothest launches in Blizzard's history, World of Warcraft: Forever requires significant computing firepower. 3,924 virtual machines work out to 18 cores and 64GB of memory per instance. Or, the company could be using a mixture of 16-core and 32-core nodes with slightly less memory.

To put the infrastructure's scale in consumer terms, we are looking at about 8,810 mainstream processors, or 7,848 high-end gaming systems with 32GB of memory each. In any event, the hardware is greatly improved compared to what World of Warcraft used to run on back in 2009.

In 2009, Blizzard said it used 10 data centers worldwide to host World of Warcraft. At the time, the infrastructure included 13,250 server blades, totaling 75,000 CPU cores and 112.5 TB of memory. By comparison, World of Warcraft: Forever leverages 6% fewer CPU cores but rocks 2.2X more memory. Modern processors are leagues faster than chips from 17 years ago. By today's standards, the bottleneck is memory capacity and bandwidth, which is why the infrastructure can run on fewer cores but has more than double the memory to compensate.

Blizzard does not specify the exact hardware that World of Warcraft: Forever runs on. However, if we were to translate the core specifications to, for example, AMD's EPYC 128-core Bergamo or 96-core Genoa chips, it could be anywhere between 275 and 365 2U server nodes, depending on which processor it uses. Therefore, World of Warcraft: Forever could be running on just eight to ten 42U server racks, a noteworthy improvement over 17 years ago.

Blizzard should have no trouble building the infrastructure for World of Warcraft: Forever. A ballpark estimate for about ten 42U server racks with EPYC chips is at least $15 million, even with today's memory pricing. But then again, since Microsoft owns Blizzard now, the company could just be tapping its parent's existing Azure platform. Technically, it is not free compute, but Blizzard would benefit from cost pricing and priority allocation of Azure's capacity.

World of Warcraft: Forever shows that a high-profile launch does not have to be a nightmare when companies are willing to invest in computing infrastructure. In this case, many would agree Blizzard is putting those 251TB to good use, although Sam Altman may say otherwise.

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