Roblox down for 73 hours (50 million users)

Postmortem from Roblox:

Starting October 28th and fully resolving on October 31st, Roblox experienced a 73-hour outage.¹ Fifty million players regularly use Roblox every day and, to create the experience our players expect, our scale involves hundreds of internal online services

The root cause was due to two issues. Enabling a relatively new streaming feature on Consul under unusually high read and write load led to excessive contention and poor performance. In addition, our particular load conditions triggered a pathological performance issue in BoltDB. The open source BoltDB system is used within Consul to manage write-ahead-logs for leader election and data replication.

via HN