When Do Zoned Namespaces SSDs Matter? A Comparative Study of Cache Workloads

Abstract

Remote object stores are widely used in public and private clouds for their simplicity and reliability, but their high latency and transfer costs make local caching essential. While RAM caches are common, they become prohibitively expensive at scale, leading to the adoption of flash-based (SSD) caches. However, conventional SSD caches suffer from unpredictable performance due to garbage collection (GC). Zoned Namespaces (ZNS) SSDs offer a promising alternative, mitigating GC-related unpredictability while retaining flash density and cost benefits. In this work, we investigate when ZNS SSDs can outperform traditional block-interface SSDs in cache workloads, and provide insights to guide system engineers in evaluating their potential advantages.