Ozone Manager Internals

This section documents the internal workings of the Ozone Manager.

📄️ Disk Layout

The Ozone Manager (OM) persists critical metadata about the Ozone namespace (volumes, buckets, keys) and its own state onto local disk. Understanding this layout is important for administration, backups, and troubleshooting.

📄️ RocksDB Schema

The Ozone Manager (OM) stores all its critical metadata, including the namespace hierarchy (volumes, buckets, keys), security information (ACLs, tokens), and operational state (multipart uploads, deleted keys), in a RocksDB key-value database. This database is located within the directory specified by ozone.om.db.dirs (typically in a subdirectory named om.db).

📄️ In-Memory Cache

To optimize performance, especially for read operations, the Ozone Manager (OM) maintains an in-memory cache of its metadata. This cache sits between client requests and the persistent RocksDB storage, serving frequently accessed information directly from the OM's Java heap memory.

📄️ Startup Sequence

TODO: File a subtask under HDDS-9862 and complete this page or section.

📄️ Roles

TODO: File a subtask under HDDS-9862 and complete this page or section.

📄️ Write Request Flow

TODO: File a subtask under HDDS-9862 and complete this page or section.

📄️ Read Request Flow

TODO: File a subtask under HDDS-9862 and complete this page or section.