name: Rook Vocabulary
description: >-
  Vocabulary and taxonomy for the Rook cloud-native storage orchestrator for
  Kubernetes, covering Ceph storage primitives, Kubernetes integration patterns,
  and operational concepts used in the Rook ecosystem.
created: '2026-05-02'
modified: '2026-05-02'
terms:
  - term: Rook
    definition: >-
      A CNCF graduated open-source cloud-native storage orchestrator for
      Kubernetes that automates deployment, configuration, and management of
      Ceph distributed storage.
    tags:
      - Core
      - CNCF
  - term: CephCluster
    definition: >-
      A Kubernetes Custom Resource (CRD) that declaratively defines a Ceph
      storage cluster managed by the Rook operator, including monitor count,
      storage scope, and daemon configuration.
    tags:
      - CRD
      - Ceph
  - term: CephBlockPool
    definition: >-
      A Kubernetes CRD that provisions a Ceph RADOS Block Device (RBD) pool,
      used as the backing store for Kubernetes StorageClasses and
      PersistentVolumes with ReadWriteOnce access.
    tags:
      - CRD
      - Block Storage
  - term: CephFilesystem
    definition: >-
      A Kubernetes CRD that provisions a CephFS shared filesystem, enabling
      ReadWriteMany PersistentVolumes for workloads requiring concurrent access
      from multiple pods.
    tags:
      - CRD
      - File Storage
  - term: CephObjectStore
    definition: >-
      A Kubernetes CRD that provisions a Ceph RADOS Gateway (RGW) providing
      S3-compatible and Swift-compatible object storage endpoints.
    tags:
      - CRD
      - Object Storage
  - term: CephObjectStoreUser
    definition: >-
      A Kubernetes CRD that creates a Ceph RGW user with access keys stored
      in a Kubernetes Secret, granting access to the CephObjectStore.
    tags:
      - CRD
      - Authentication
  - term: RGW
    definition: >-
      Ceph RADOS Gateway — the HTTP/REST gateway component that exposes
      S3-compatible and Swift-compatible object storage APIs. Rook provisions
      RGW instances via the CephObjectStore CRD.
    tags:
      - Ceph
      - Object Storage
  - term: RBD
    definition: >-
      RADOS Block Device — the Ceph block storage mechanism that provides
      raw block volumes to Kubernetes nodes via the rbd kernel module or
      the ceph-csi driver.
    tags:
      - Ceph
      - Block Storage
  - term: CephFS
    definition: >-
      Ceph Filesystem — the distributed POSIX-compliant filesystem provided
      by Ceph, managed through the CephFilesystem CRD and exposed via
      the ceph-csi driver or the kernel CephFS client.
    tags:
      - Ceph
      - File Storage
  - term: Ceph Monitor (Mon)
    definition: >-
      A Ceph daemon that maintains the cluster map and quorum. Rook manages
      monitor count and placement through the CephCluster spec.mon field.
    tags:
      - Ceph
      - Architecture
  - term: Ceph Manager (Mgr)
    definition: >-
      A Ceph daemon providing cluster monitoring, dashboard, and module
      extensibility. Managed through the CephCluster spec.mgr field.
    tags:
      - Ceph
      - Architecture
  - term: OSD
    definition: >-
      Object Storage Daemon — the Ceph process that stores data on individual
      disks. Rook automatically provisions OSDs on nodes and devices matching
      the CephCluster storage scope configuration.
    tags:
      - Ceph
      - Architecture
  - term: StorageClass
    definition: >-
      A Kubernetes resource that references a Rook-managed Ceph pool as the
      provisioner, enabling dynamic provisioning of PersistentVolumes using
      the ceph-csi driver.
    tags:
      - Kubernetes
  - term: PersistentVolumeClaim
    definition: >-
      A Kubernetes resource used by applications to request storage from a
      Rook-managed StorageClass. Rook fulfills the claim by dynamically
      provisioning a Ceph RBD or CephFS volume.
    tags:
      - Kubernetes
  - term: ceph-csi
    definition: >-
      The Container Storage Interface driver for Ceph, used by Rook to expose
      Ceph block (RBD) and filesystem (CephFS) storage to Kubernetes workloads
      through the CSI standard.
    tags:
      - Kubernetes
      - Integration
  - term: Operator
    definition: >-
      The Rook Kubernetes Operator — a controller running in the cluster that
      watches CRDs and reconciles the desired state of Ceph storage resources.
    tags:
      - Kubernetes
      - Architecture
  - term: Toolbox
    definition: >-
      A Rook debug pod that provides the ceph CLI and other debugging tools
      for inspecting cluster health and executing Ceph commands directly
      against the cluster.
    tags:
      - Operations
  - term: S3-Compatible
    definition: >-
      The Ceph Object Storage gateway supports the Amazon S3 API, allowing
      applications using the AWS SDK or S3-compatible clients to interact
      with Rook-managed Ceph object storage.
    tags:
      - Object Storage
      - Integration
  - term: Failure Domain
    definition: >-
      The unit of fault isolation used by Ceph for data replication. Common
      failure domains include host and osd. Configured per CephBlockPool
      and CephFilesystem data pool.
    tags:
      - Architecture
      - Reliability
  - term: CRUSH
    definition: >-
      Controlled Replication Under Scalable Hashing — the Ceph algorithm for
      calculating object placement across OSDs based on the cluster topology
      and failure domains.
    tags:
      - Ceph
      - Architecture