Introduction to the Special Section on OSDI’18

This special section of the ACM Transactions on Storage presents two articles from the 13th USENIX Symposium on Operating System Design and Implementation (OSDI’18). OSDI’18 contained 47 exceptionally strong articles across a range of topics: file and storage systems, networking, scheduling, security, formal verification, graph processing, machine learning, programming languages, fault-tolerance and reliability, debugging, and, of course, operating systems design and implementation. The two high-quality articles we have selected for TOS focus, not surprisingly, on file and storage systems. The first article is “Write-Optimized and High-Performance Hashing Index Scheme for Persistent Memory” by Pengfei Zuo, Yu Hua, and Jie Wu. This article introduces an elegant hashing data structure for non-volatile memory (NVM), called level hashing. Level hashing optimizes for NVM with low-overhead consistency mechanisms and by reducing the number of write operations. Level hashing has particularly interesting algorithms for performing in-place resizing of the hash table. The second article is “Finding Crash-Consistency Bugs with Bounded Black-Box Crash Testing” by Jayashree Mohan, Ashlie Martinez, Soujanya Ponnapalli, Pandian Raju, and Vijay Chidambaram. CrashMonkey and Ace are a set of tools to systematically find crash-consistency bugs in Linux file systems. CrashMonkey tests a target file system by simulating power-loss crashes and then checks if the file system recovers to a correct state. Ace automatically generates interesting workloads to stress the target file system; Ace is particularly innovative in how it explores the infinite space of possible workloads. With these new tools, the authors have found many difficult crash-consistency bugs, including 10 previously unknown bugs in widely used, mature Linux file systems and one in FSCQ, a verified file system. We hope you will find these articles interesting and inspiring!