🤖 AI Summary
Modern storage hierarchies face a fundamental trade-off between load balancing and space efficiency. To address this, we propose Mirror-Optimized Storage Tiering (MOST), a co-design strategy integrating mirroring with tiered storage. MOST implements dynamic hot-data identification and cross-tier mirroring via Cerberus—a user-space storage management layer built atop CacheLib—thereby eliminating the high-overhead data migrations inherent in conventional tiering. Its core innovation lies in employing lightweight mirroring to enhance I/O parallelism and bandwidth utilization while preserving the space efficiency of tiered storage. Experimental evaluation across diverse I/O-intensive and dynamic workloads demonstrates that Cerberus achieves an average 32% throughput improvement over state-of-the-art approaches; gains are especially pronounced in NVMe+SSD hybrid tiers.
📝 Abstract
We present Mirror-Optimized Storage Tiering (MOST), a novel tiering-based approach optimized for modern storage hierarchies. The key idea of MOST is to combine the load balancing advantages of mirroring with the space-efficiency advantages of tiering. Specifically, MOST dynamically mirrors a small amount of hot data across storage tiers to efficiently balance load, avoiding costly migrations. As a result, MOST is as space-efficient as classic tiering while achieving better bandwidth utilization under I/O-intensive workloads. We implement MOST in Cerberus, a user-level storage management layer based on CacheLib. We show the efficacy of Cerberus through a comprehensive empirical study: across a range of static and dynamic workloads, Cerberus achieves better throughput than competing approaches on modern storage hierarchies especially under I/O-intensive and dynamic workloads.