EOS Open Storage documentation

The EOS project’s own documentation.

What it anchors

• EOS is CERN’s open-source disk storage system, built on the XRootD framework as its remote access protocol.
• The namespace runs as an in-memory cache with QuarkDB as the external key-value store for persistence — the redesign that lifted the earlier ceiling of “as much metadata as fits in one machine’s RAM”.
• Access through FUSE (POSIX-like), HTTPS/WebDAV, XRootD, gRPC, S3 and SMB.
• Written mostly in C/C++, running on commodity hardware with disks in JBOD.