Discord's 2.5-hour RCA was a correlation problem, not a data problem. Anyone solved this?

On June 19, Discord had message delivery lag up to 4 minutes for a subset of users. Root cause was Redis keyspace eviction from memory pressure caused by an unrelated deploy. The post-mortem line that stuck: the team had Redis metrics, latency dashboards, and error rates visible throughout, and the causal chain still took 2.5 hours to reconstruct by hand.

Every link was instrumented. The sequence only became obvious after someone stitched together timestamps across systems, matching numbers that were off by a few seconds because two services logged in different time zones.

I've done that stitching. It's the same unglamorous 90 minutes whether you're 2 years into SRE or 10.

What I often find myself coming back to is whether this is a tooling problem or a mental model problem. Discord isn't understaffed or undertooled. Even if a system had flagged the correlation automatically, someone still has to decide whether to trust that read or keep looking. That validation step has a floor.

Has anyone found a setup that actually shortens the reconstruction phase, not the detection phase?