FROM CHAOS TO CONTROL: ADDRESSING SHARD DISTRIBUTION CHALLENGES IN M3DB WITH SUBCLUSTERS

Summary from the TLDR DevOps newsletter

Uber redesigned M3DB's shard placement for large clusters by partitioning nodes into self-contained subclusters that own non-overlapping portions of the shard space. The approach reduces failure and maintenance blast radius, allows operations on separate subclusters to run in parallel, and uses a greedy migration algorithm to keep shard distribution balanced during scaling.