MiniWear: Minimizing Flash Wear via Hybrid Persistent Cache for Extended EF-SMR Lifetime

As the huge discrepancy between traffic and capacity persists, the lifetime of flash in EF-SMR systems faces a grave issue. EF-SMR systems combine NAND flash with Shingled Magnetic Recording (SMR) disks to achieve both low cost and high performance. However, previous research has primarily focused on issues such as write amplification and tail-latency in EF-SMR disks, overlooking the critical issue of flash lifetime. Studying the durability of EF-SMR systems is essential for developing future high-performance, low-cost storage solutions.This paper presents MiniWear, a hybrid persistent cache (PC) design aimed at extending the lifetime of EF-SMR systems. MiniWear adopts a hybrid medium persistent cache and proposes a customized scheduling strategy to reduce flash wear without impacting the EF-SMR system performance. At the hardware level, the hybrid PC of EF-SMR, composed of flash and SMR disk, is organized into Flash-PC and SMR-PC. At the software level, a fine-grained scheduling strategy is proposed to better manage PC resources. Additionally, we introduce a proactive balancing strategy to address PC resource idleness. Experimental results show that, compared to existing methods, MiniWear can reduce flash wear by up to 66.67%.