Balloon-ZNS: Constructing High-Capacity and Low-Cost ZNS SSDs with Built-in Compression

ZNS SSDs are emerging storage devices promising low cost, high performance, and software definability. This paper proposes Balloon-ZNS that enables transparent compression in ZNS SSDs to enhance cost efficiency. ZNS SSDs, unlike traditional SSDs, require data pages to be stored in logical zones and flash blocks with aligned offsets, conflicting with the management of compressed, variable-length pages. Motivated by a key observation that compressibility locality widely exists in data streams, Balloon-ZNS employs a compressibility-adaptive, slot-aligned storage management scheme to address the intractable conflict. Evaluation with RocksDB shows Balloon-ZNS can reap more than 80% of the compression gain while achieving 7.3% lower to 14.4% higher throughput than a vanilla ZNS SSD, on average, when data compressibility is not poor.