Reliable Writeback for Client-side Flash Caches

Modern data centers are increasingly using shared storage solutions for ease of management. Data is cached on the client side on inexpensive and high-capacity flash devices, helping improve performance and reduce contention on the storage side. Currently, write-through caching is used because it ensures consistency and durability under client failures, but it offers poor performance for write-heavy workloads.

In this work, we propose two write-back based caching policies, called write-back flush and write-back persist, that provide strong reliability guarantees, under two different client failure models. These policies rely on storage applications, such as file systems and databases, issuing write barriers to persist their data reliably on storage media. Our evaluation shows that these policies perform close to write-back caching, significantly outperforming write-through caching, for both read-heavy and write-heavy workloads.