McDipper: A key-value cache for Flash storage

What this post added

This post introduces McDipper, a highly performant flash-based cache server that is Memcache protocol compatible. It addresses the challenge of efficiently caching large datasets with moderate to low request rates by leveraging flash storage. McDipper is presented as a drop-in replacement for Memcached, offering improved capacity and performance. The post details the technical challenges in achieving feature parity with Memcached, including handling race conditions between sets and invalidations, and introduces solutions like delete hold-offs and read-modify-write operations. A significant application of McDipper is highlighted in Facebook's photo infrastructure, where it serves over 150 Gb/s from forward caches in the CDN, drastically reducing server counts and improving latency. The post also emphasizes the importance of configurability and collaboration in the successful deployment of such infrastructure.