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Archil’s FUSE-based file system is designed to be fully compatible with all applications which run on a local, POSIX file system. If you discover behavior that you believe deviates from POSIX, please contact us by emailing support@archil.com, and we will address the underlying issue. We are continuously testing our adherence to POSIX, using the same test suite as the XFS file systems.

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POSIX compatibility details

Archil disks are designed to be broadly compatible with POSIX semantics, even when the underlying data sources are not POSIX compatible, like Amazon S3. When needed, the Archil storage service emulates file operations on data sources. Today, Archil supports the following POSIX features:
  • All read and write operations, including random writes and appends
  • Symbolic links (ln -s)
  • Hard Links (ln)
  • Atomic renames, including directory renames (mv)1
  • POSIX locks, including flock and fcntl2
  • Anonymous files (unlink after opening)
  • File modes
  • File ownership
  • Extended attributes (with the --enable-xattrs flag)
1. A rename is atomic — a reader on another client sees either the old name or the new name, never a partial result. Archil’s storage system is fully consistent; a client’s cached view can lag briefly and refreshes with archil invalidate-cache.
2. POSIX locks (flock/fcntl) are honored between processes on a single client, not across clients that share a disk. Today only one client can open a file for writing, so cross-client lock contention doesn’t arise; coordinate access across clients with the checkout/checkin ownership model. We are actively working on adding support for the following features:
  • File ACLs
  • renameat2 flags, such as RENAME_WHITEOUT

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Application support

As a result of our broad compatibility with POSIX, Archil is compatible with all applications which run on a local, POSIX file system. This includes:
  • Version control systems, such as Git (including large repositories, git clone, git checkout, and git status), Mercurial, and Subversion
  • Databases, such as PostgreSQL, MySQL, and SQLite
  • Build tools and compilers, such as Make, CMake, GCC, and Clang
  • Archive and compression tools, such as tar, gzip, zip, and rsync
  • Editors and IDEs, such as Vim, Emacs, and VS Code
  • Containers — mount in a container via a bind mount from the host or FUSE inside the container

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Limits

  • Path length — on a disk synchronized to a data source, a file’s full path can’t exceed the data source’s object-key length limit (1,024 characters for Amazon S3).