Blizzard has provided a very long update on the Diablo II: Resurrected server issues. The update is incredibly detailed and, citing transparency, breaks down into detail all the different issues that have been bumping up against each other since launch and unfortunately leading to outages and inability to log in.
Players have been frustrated, and while the team keeps addressing issues as they pop up, they’re also working on ways to prevent these outages. One recent change should limit any potential lost progress to just a couple of minutes and are continuing to work on fixing that completely.
The other server issues are related to heavy demand. Last weekend demand was even larger than at launch. Blizzard keeps the final records in a global database and divides individual data across regional databases that regularly write to the global database but are intended to handle the load.
Well, the demand, sometimes hundreds of thousands of people, overloaded it and caused timeouts. Part of the work they did was to roll back the Friday update last week and hope that the issues on Saturday wouldn’t be repeated on Sunday but again there was huge demand. Sunday’s issues made it clear that the database didn’t have any time to catch up because of all the connection attempts.
One of the fascinating reveals about Diablo II: Resurrected is that it’s built on the original code. That legacy code is cited in the blog update as one of the sources that is impeding performance. Development included updating to work with modern tech but again a lot of these issues are because of the older code. Back in 2001, there wasn’t as much potential simultaneous demand as there is in 2021. So what are they doing now? They’re adding rate limits to pace demand, and creating a login queue as well to prevent a rush to the servers. This is in addition to changing data save to use regional servers more and write to the global database a little less.
You can read the entire update, with all of the engineering and details on server outage causes and work right here on the Diablo II site.