Driving Content Delivery Efficiency Through Classifying Cache Misses

Netflix's Open Connect program is a content delivery network (CDN) that aims to provide the best quality of experience (QoE) to its members by localizing content delivery through partnerships with internet service providers (ISPs) worldwide. The program uses custom-built servers called Open Connect Appliances (OCAs) that are designed for efficiency and cost-effectiveness. To evaluate the efficiency of Open Connect, Netflix uses a framework to identify sources of inefficiencies, specifically cache misses, which occur when bytes are not served from the best available OCA for a given client. Cache misses are classified into three categories: content misses, health misses, and other misses. Content misses occur when files are not found on OCAs in the local site, while health misses occur when the local site's OCA hardware resources are saturated. Netflix logs two critical data components to compute cache misses: steering playback manifest logs and OCA server logs. These logs are joined to compute detailed cache miss metrics at different aggregation levels. The system architecture for computing cache misses involves log emission, log consolidation, log enrichment, and streaming window-based joins. The data model used to evaluate cache misses allows for replaying logic offline and in simulations with variable parameters to test new conditions and features without impacting production traffic.