Quicksilver v2: evolution of a globally distributed key-value store (Part 2)

What this post added

This post details the evolution of Cloudflare's Quicksilver globally distributed key-value store to version 2. It addresses scalability challenges faced by V1 and V1.5 by introducing a new architecture that separates storage replicas from caching proxies. Key innovations include identifying and offloading 'cold keys' to dedicated storage servers, implementing a relay mechanism to manage connections from caching proxies to replicas, and introducing reactive prefetching of cache misses to improve cache hit rates to 99.9%. The post also discusses the need for further cache hit rate improvements for latency-sensitive instances like 'dnsv2' and the reintroduction of data center-wide sharded caches before accessing replicas.