CrossLFS

CrossLFS, short for Cross-Platform Log-Structured File System, is an open-source, cross-platform file system that implements log-structured storage semantics to provide robust crash recovery, fast writes, and consistent metadata handling across operating systems. It is designed to run in user space and to offer similar file-system semantics on Linux, macOS, and Windows through platform-compatible adapters and bridges.

CrossLFS is implemented as a user-space file system. On Linux and macOS, it runs over FUSE (or FUSE-like interfaces); on Windows, it uses WinFsp and a compatibility layer to present a POSIX-like view. Data and metadata are stored in a linear log divided into segments, with a metadata index mapping path names to log offsets. A background garbage collector reclaims stale entries. The design emphasizes crash resilience, featuring transactional updates and commit semantics for metadata operations. Optional encryption and compression are supported to address security and space efficiency.

Features include POSIX-like semantics via a stable API, atomic file operations, and support for snapshots and versioning. The system offers write buffering, deduplication options, and space-efficient indexing, along with hooks for export/import and pluggable backends for local and networked storage. CrossLFS aims to provide a consistent development and operational experience across platforms, making it suitable for mixed-OS environments.

Use cases include reproducible development environments, cross-platform backups, data-intensive workloads that benefit from fast appends, and archival scenarios where crash recovery is essential. The project emphasizes portability and safety, prioritizing transparent behavior and recoverable storage over aggressive performance optimizations.

History and status: Development began in 2019 by a consortium of researchers and engineers. The first public release appeared in 2020, with subsequent major and minor releases. It is maintained by an open community and released under an open-source license.