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Ceph Cluster CRD

Rook allows creation and customization of storage clusters through the custom resource definitions (CRDs). There are two different modes to create your cluster, depending on whether storage can be dynamically provisioned on which to base the Ceph cluster.

  1. Specify host paths and raw devices
  2. Specify the storage class Rook should use to consume storage via PVCs

Following is an example for each of these approaches.

Host-based Cluster

To get you started, here is a simple example of a CRD to configure a Ceph cluster with all nodes and all devices. Next example is where Mons and OSDs are backed by PVCs. More examples are included later in this doc.

NOTE: In addition to your CephCluster object, you need to create the namespace, service accounts, and RBAC rules for the namespace you are going to create the CephCluster in. These resources are defined in the example common.yaml.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    # see the "Cluster Settings" section below for more details on which image of ceph to run
    image: ceph/ceph:v14.2.5
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: true
  storage:
    useAllNodes: true
    useAllDevices: true

PVC-based Cluster

NOTE: Kubernetes version 1.13.0 or greater is required to provision OSDs on PVCs.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    volumeClaimTemplate:
      spec:
        storageClassName: local-storage
        resources:
          requests:
            storage: 10Gi
  storage:
   storageClassDeviceSets:
    - name: set1
      count: 3
      portable: false
      tuneSlowDeviceClass: false
      volumeClaimTemplates:
      - metadata:
          name: data
        spec:
          resources:
            requests:
              storage: 10Gi
          # IMPORTANT: Change the storage class depending on your environment (e.g. local-storage, gp2)
          storageClassName: local-storage
          volumeMode: Block
          accessModes:
            - ReadWriteOnce

Settings

Settings can be specified at the global level to apply to the cluster as a whole, while other settings can be specified at more fine-grained levels. If any setting is unspecified, a suitable default will be used automatically.

Cluster metadata

  • name: The name that will be used internally for the Ceph cluster. Most commonly the name is the same as the namespace since multiple clusters are not supported in the same namespace.
  • namespace: The Kubernetes namespace that will be created for the Rook cluster. The services, pods, and other resources created by the operator will be added to this namespace. The common scenario is to create a single Rook cluster. If multiple clusters are created, they must not have conflicting devices or host paths.

Cluster Settings

  • external:
    • enable: if true, the cluster will not be managed by Rook but via an external entity. This mode is intended to connect to an existing cluster. In this case, Rook will only consume the external cluster. However, Rook will be able to deploy various daemons in Kubernetes such as object gateways, mds and nfs if an image is provided and will refuse otherwise. If this setting is enabled all the other options will be ignored except cephVersion.image and dataDirHostPath. See external cluster configuration. If cephVersion.image is left blank, Rook will refuse the creation of extra CRs like object, file and nfs.
  • cephVersion: The version information for launching the ceph daemons.
    • image: The image used for running the ceph daemons. For example, ceph/ceph:v13.2.6-20190604 or ceph/ceph:v14.2.5. For more details read the container images section. For the latest ceph images, see the Ceph DockerHub. To ensure a consistent version of the image is running across all nodes in the cluster, it is recommended to use a very specific image version. Tags also exist that would give the latest version, but they are only recommended for test environments. For example, the tag v14 will be updated each time a new nautilus build is released. Using the v14 or similar tag is not recommended in production because it may lead to inconsistent versions of the image running across different nodes in the cluster.
    • allowUnsupported: If true, allow an unsupported major version of the Ceph release. Currently mimic and nautilus are supported, so octopus would require this to be set to true. Should be set to false in production.
  • dataDirHostPath: The path on the host (hostPath) where config and data should be stored for each of the services. If the directory does not exist, it will be created. Because this directory persists on the host, it will remain after pods are deleted. Following paths and any of their subpaths must not be used: /etc/ceph, /rook or /var/log/ceph.
    • On Minikube environments, use /data/rook. Minikube boots into a tmpfs but it provides some directories where files can be persisted across reboots. Using one of these directories will ensure that Rook's data and configuration files are persisted and that enough storage space is available.
    • WARNING: For test scenarios, if you delete a cluster and start a new cluster on the same hosts, the path used by dataDirHostPath must be deleted. Otherwise, stale keys and other config will remain from the previous cluster and the new mons will fail to start. If this value is empty, each pod will get an ephemeral directory to store their config files that is tied to the lifetime of the pod running on that node. More details can be found in the Kubernetes empty dir docs.
  • skipUpgradeChecks: if set to true Rook won't perform any upgrade checks on Ceph daemons during an upgrade. Use this at YOUR OWN RISK, only if you know what you're doing. To understand Rook's upgrade process of Ceph, read the upgrade doc.
  • dashboard: Settings for the Ceph dashboard. To view the dashboard in your browser see the dashboard guide.
    • enabled: Whether to enable the dashboard to view cluster status
    • urlPrefix: Allows to serve the dashboard under a subpath (useful when you are accessing the dashboard via a reverse proxy)
    • port: Allows to change the default port where the dashboard is served
    • ssl: Whether to serve the dashboard via SSL, ignored on Ceph versions older than 13.2.2
  • network: The network settings for the cluster
    • hostNetwork: uses network of the hosts instead of using the SDN below the containers.
  • mon: contains mon related options mon settings For more details on the mons and when to choose a number other than 3, see the mon health design doc.
  • mgr: manager top level section
    • modules: is the list of Ceph manager modules to enable
  • rbdMirroring: The settings for rbd mirror daemon(s). Configuring which pools or images to be mirrored must be completed in the rook toolbox by running the rbd mirror command.
    • workers: The number of rbd daemons to perform the rbd mirroring between clusters.
  • annotations: annotations configuration settings
  • placement: placement configuration settings
  • resources: resources configuration settings
  • priorityClassNames: priority class names configuration settings
  • storage: Storage selection and configuration that will be used across the cluster. Note that these settings can be overridden for specific nodes.
    • useAllNodes: true or false, indicating if all nodes in the cluster should be used for storage according to the cluster level storage selection and configuration values. If individual nodes are specified under the nodes field, then useAllNodes must be set to false.
    • nodes: Names of individual nodes in the cluster that should have their storage included in accordance with either the cluster level configuration specified above or any node specific overrides described in the next section below. useAllNodes must be set to false to use specific nodes and their config. See node settings below.
    • config: Config settings applied to all OSDs on the node unless overridden by devices or directories. See the config settings below.
    • storage selection settings
    • Storage Class Device Sets
  • disruptionManagement: The section for configuring management of daemon disruptions
    • managePodBudgets: if true, the operator will create and manage PodDisruptionBudgets for OSD, Mon, RGW, and MDS daemons. OSD PDBs are managed dynamically via the strategy outlined in the design. The operator will block eviction of OSDs by default and unblock them safely when drains are detected.
    • osdMaintenanceTimeout: is a duration in minutes that determines how long an entire failureDomain like region/zone/host will be held in noout (in addition to the default DOWN/OUT interval) when it is draining. This is only relevant when managePodBudgets is true. The default value is 30 minutes.
    • manageMachineDisruptionBudgets: if true, the operator will create and manage MachineDisruptionBudgets to ensure OSDs are only fenced when the cluster is healthy. Only available on OpenShift.
    • machineDisruptionBudgetNamespace: the namespace in which to watch the MachineDisruptionBudgets.
  • removeOSDsIfOutAndSafeToRemove: If true the operator will remove the OSDs that are down and whose data has been restored to other OSDs. In Ceph terms, the osds are out and safe-to-destroy when then would be removed.

Ceph container images

Official releases of Ceph Container images are available from Docker Hub.

These are general purpose Ceph container with all necessary daemons and dependencies installed.

TAG MEANING
vRELNUM Latest release in this series (e.g., v14 = Nautilus)
vRELNUM.Y Latest stable release in this stable series (e.g., v14.2)
vRELNUM.Y.Z A specific release (e.g., v14.2.5)
vRELNUM.Y.Z-YYYYMMDD A specific build (e.g., v14.2.5-20191203)

A specific will contain a specific release of Ceph as well as security fixes from the Operating System.

Mon Settings

  • count: Set the number of mons to be started. The number should be odd and between 1 and 9. If not specified the default is set to 3 and allowMultiplePerNode is also set to true.
  • allowMultiplePerNode: Enable (true) or disable (false) the placement of multiple mons on one node. Default is false.
  • volumeClaimTemplate: A PersistentVolumeSpec used by Rook to create PVCs for monitor storage. This field is optional, and when not provided, HostPath volume mounts are used. The current set of fields from template that are used are storageClassName and the storage resource request and limit. The default storage size request for new PVCs is 10Gi. Ensure that associated storage class is configured to use volumeBindingMode: WaitForFirstConsumer. This setting only applies to new monitors that are created when the requested number of monitors increases, or when a monitor fails and is recreated. An example CRD configuration is provided below.

If these settings are changed in the CRD the operator will update the number of mons during a periodic check of the mon health, which by default is every 45 seconds.

To change the defaults that the operator uses to determine the mon health and whether to failover a mon, the following environment variables can be changed in operator.yaml. The intervals should be small enough that you have confidence the mons will maintain quorum, while also being long enough to ignore network blips where mons are failed over too often.

  • ROOK_MON_HEALTHCHECK_INTERVAL: The frequency with which to check if mons are in quorum (default is 45 seconds)
  • ROOK_MON_OUT_TIMEOUT: The interval to wait before marking a mon as "out" and starting a new mon to replace it in the quorum (default is 600 seconds)

Mgr Settings

You can use the cluster CR to enable or disable any manager module. This can be configured like so:

mgr:
  modules:
  - name: <name of the module>
    enabled: true

Some modules will have special configuration to ensure the module is fully functional after being enabled. Specifically:

  • pg_autoscaler: Rook will configure all new pools with PG autoscaling by setting: osd_pool_default_pg_autoscale_mode = on

Node Settings

In addition to the cluster level settings specified above, each individual node can also specify configuration to override the cluster level settings and defaults. If a node does not specify any configuration then it will inherit the cluster level settings.

  • name: The name of the node, which should match its kubernetes.io/hostname label.
  • config: Config settings applied to all OSDs on the node unless overridden by devices or directories. See the config settings below.
  • storage selection settings

When useAllNodes is set to true, Rook attempts to make Ceph cluster management as hands-off as possible while still maintaining reasonable data safety. If a usable node comes online, Rook will begin to use it automatically. To maintain a balance between hands-off usability and data safety, Nodes are removed from Ceph as OSD hosts only (1) if the node is deleted from Kubernetes itself or (2) if the node has its taints or affinities modified in such a way that the node is no longer usable by Rook. Any changes to taints or affinities, intentional or unintentional, may affect the data reliability of the Ceph cluster. In order to help protect against this somewhat, deletion of nodes by taint or affinity modifications must be "confirmed" by deleting the Rook-Ceph operator pod and allowing the operator deployment to restart the pod.

For production clusters, we recommend that useAllNodes is set to false to prevent the Ceph cluster from suffering reduced data reliability unintentionally due to a user mistake. When useAllNodes is set to false, Rook relies on the user to be explicit about when nodes are added to or removed from the Ceph cluster. Nodes are only added to the Ceph cluster if the node is added to the Ceph cluster resource. Similarly, nodes are only removed if the node is removed from the Ceph cluster resource.

Node Updates

Nodes can be added and removed over time by updating the Cluster CRD, for example with kubectl -n rook-ceph edit cephcluster rook-ceph. This will bring up your default text editor and allow you to add and remove storage nodes from the cluster. This feature is only available when useAllNodes has been set to false.

Storage Selection Settings

Below are the settings available, both at the cluster and individual node level, for selecting which storage resources will be included in the cluster.

  • useAllDevices: true or false, indicating whether all devices found on nodes in the cluster should be automatically consumed by OSDs. Not recommended unless you have a very controlled environment where you will not risk formatting of devices with existing data. When true, all devices will be used except those with partitions created or a local filesystem. Is overridden by deviceFilter if specified.
  • deviceFilter: A regular expression for short kernel names of devices (e.g. sda) that allows selection of devices to be consumed by OSDs. If individual devices have been specified for a node then this filter will be ignored. This field uses golang regular expression syntax. For example:
    • sdb: Only selects the sdb device if found
    • ^sd.: Selects all devices starting with sd
    • ^sd[a-d]: Selects devices starting with sda, sdb, sdc, and sdd if found
    • ^s: Selects all devices that start with s
    • ^[^r]: Selects all devices that do not start with r
  • devicePathFilter: A regular expression for device paths (e.g. /dev/disk/by-path/pci-0:1:2:3-scsi-1) that allows selection of devices to be consumed by OSDs. If individual devices or deviceFilter have been specified for a node then this filter will be ignored. This field uses golang regular expression syntax. For example:
    • ^/dev/sd.: Selects all devices starting with sd
    • ^/dev/disk/by-path/pci-.*: Selects all devices which are connected to PCI bus
  • devices: A list of individual device names belonging to this node to include in the storage cluster.
    • name: The name of the device (e.g., sda)
    • config: Device-specific config settings. See the config settings below
  • directories: A list of directory paths that will be included in the storage cluster. Note that using two directories on the same physical device can cause a negative performance impact. Following paths and any of their subpaths must not be used: /etc/ceph, /rook or /var/log/ceph.
    • path: The path on disk of the directory (e.g., /rook/storage-dir)
    • config: Directory-specific config settings. See the config settings below
  • storageClassDeviceSets: Explained in Storage Class Device Sets

Storage Class Device Sets

The following are the settings for Storage Class Device Sets which can be configured to create OSDs that are backed by block mode PVs.

  • name: A name for the set.
  • count: The number of devices in the set.
  • resources: The CPU and RAM requests/limits for the devices. (Optional)
  • placement: The placement criteria for the devices. (Optional) Default is no placement criteria. It is recommended to configure the placement such that the OSDs will be as evenly spread across nodes as possible. At a minimum, anti-affinity should be added so at least one OSD will be placed on each available nodes. However, if there are more OSDs than nodes, this anti-affinity will not be effective. Another placement scheme to consider is to add labels to the nodes in such a way that the OSDs can be grouped on those nodes, create multiple storageClassDeviceSets, and add node affinity to each of the device sets that will place the OSDs in those sets of nodes.
  • portable: If true, the OSDs will be allowed to move between nodes during failover. This requires a storage class that supports portability (e.g. aws-ebs, but not the local storage provisioner). If false, the OSDs will be assigned to a node permanently. Rook will configure Ceph's CRUSH map to support the portability.
  • tuneSlowDeviceClass: If true, because the OSD can be on a slow device class, Rook will adapt to that by tuning the OSD process. This will make Ceph perform better under that slow device.
  • volumeClaimTemplates: A list of PVC templates to use for provisioning the underlying storage devices.
    • resources.requests.storage: The desired capacity for the underlying storage devices.
    • storageClassName: The StorageClass to provision PVCs from. Default would be to use the cluster-default StorageClass. This StorageClass should provide a raw block device or logical volume. Other types are not supported.
    • volumeMode: The volume mode to be set for the PVC. Which should be Block
    • accessModes: The access mode for the PVC to be bound by OSD.

OSD Configuration Settings

The following storage selection settings are specific to Ceph and do not apply to other backends. All variables are key-value pairs represented as strings.

  • metadataDevice: Name of a device to use for the metadata of OSDs on each node. Performance can be improved by using a low latency device (such as SSD or NVMe) as the metadata device, while other spinning platter (HDD) devices on a node are used to store data. Provisioning will fail if the user specifies a metadataDevice but that device is not used as a metadata device by Ceph. Notably, ceph-volume will not use a device of the same device class (HDD, SSD, NVMe) as OSD devices for metadata, resulting in this failure.
  • storeType: filestore or bluestore, the underlying storage format to use for each OSD. The default is set dynamically to bluestore for devices, while filestore is the default for directories. Set this store type explicitly to override the default. Warning: Bluestore is not recommended for directories in production. Bluestore does not purge data from the directory and over time will grow without the ability to compact or shrink.
  • databaseSizeMB: The size in MB of a bluestore database. Include quotes around the size.
  • walSizeMB: The size in MB of a bluestore write ahead log (WAL). Include quotes around the size.
  • journalSizeMB: The size in MB of a filestore journal. Include quotes around the size.
  • osdsPerDevice**: The number of OSDs to create on each device. High performance devices such as NVMe can handle running multiple OSDs. If desired, this can be overridden for each node and each device.
  • encryptedDevice**: Encrypt OSD volumes using dmcrypt ("true" or "false"). By default this option is disabled. See encryption for more information on encryption in Ceph.

** NOTE: Depending on the Ceph image running in your cluster, OSDs will be configured differently. Newer images will configure OSDs with ceph-volume, which provides support for osdsPerDevice, encryptedDevice, as well as other features that will be exposed in future Rook releases. OSDs created prior to Rook v0.9 or with older images of Luminous and Mimic are not created with ceph-volume and thus would not support the same features. For ceph-volume, the following images are supported:

  • Luminous 12.2.10 or newer
  • Mimic 13.2.3 or newer
  • Nautilus

Annotations Configuration Settings

Annotations can be specified so that the Rook components will have those annotations added to them.

You can set annotations for Rook components for the list of key value pairs:

  • all: Set annotations for all components
  • mgr: Set annotations for MGRs
  • mon: Set annotations for mons
  • osd: Set annotations for OSDs
  • rbdmirror: Set annotations for RBD Mirrors

When other keys are set, all will be merged together with the specific component.

Placement Configuration Settings

Placement configuration for the cluster services. It includes the following keys: mgr, mon, osd, rbdmirror and all. Each service will have its placement configuration generated by merging the generic configuration under all with the most specific one (which will override any attributes).

A Placement configuration is specified (according to the kubernetes PodSpec) as:

The mon pod does not allow Pod affinity or anti-affinity. Instead, mons have built-in anti-affinity with each other through the operator. The operator determines which nodes should run a mon. Each mon is then tied to a node with a node selector using a hostname. See the mon design doc for more details on the mon failover design.

The Rook Ceph operator creates a Job called rook-ceph-detect-version to detect the full Ceph version used by the given cephVersion.image. The placement from the mon section is used for the Job.

Cluster-wide Resources Configuration Settings

Resources should be specified so that the Rook components are handled after Kubernetes Pod Quality of Service classes. This allows to keep Rook components running when for example a node runs out of memory and the Rook components are not killed depending on their Quality of Service class.

You can set resource requests/limits for Rook components through the Resource Requirements/Limits structure in the following keys:

  • mgr: Set resource requests/limits for MGRs
  • mon: Set resource requests/limits for mons
  • osd: Set resource requests/limits for OSDs
  • rbdmirror: Set resource requests/limits for RBD Mirrors
  • prepareosd: Set resource requests/limits for OSD prepare job
  • crashcollector: Set resource requests/limits for crash. This pod runs wherever there is a Ceph pod running. It scrapes for Ceph daemon core dumps and sends them to the Ceph manager crash module so that core dumps are centralized and can be easily listed/accessed. You can read more about the Ceph Crash module.

In order to provide the best possible experience running Ceph in containers, Rook internally enforces minimum memory limits if resource limits are passed. If a user configures a limit or request value that is too low, Rook will refuse to run the pod(s). Here are the current minimum amounts of memory in MB to apply so that Rook will agree to run Ceph pods:

  • mon: 1024MB
  • mgr: 512MB
  • osd: 2048MB
  • mds: 4096MB
  • rbdmirror: 512MB

Rook does not enforce any minimum limit nor request on the following:

  • prepare OSD pod: This pod commonly takes up to 50MB, but depending on the OSD scenario may need more memory. 100MB would be more conservative.
  • crashcollector pod: This pod commonly takes around 60MB.

Resource Requirements/Limits

For more information on resource requests/limits see the official Kubernetes documentation: Kubernetes - Managing Compute Resources for Containers

  • requests: Requests for cpu or memory.
    • cpu: Request for CPU (example: one CPU core 1, 50% of one CPU core 500m).
    • memory: Limit for Memory (example: one gigabyte of memory 1Gi, half a gigabyte of memory 512Mi).
  • limits: Limits for cpu or memory.
    • cpu: Limit for CPU (example: one CPU core 1, 50% of one CPU core 500m).
    • memory: Limit for Memory (example: one gigabyte of memory 1Gi, half a gigabyte of memory 512Mi).

Priority Class Names Configuration Settings

Priority class names can be specified so that the Rook components will have those priority class names added to them.

You can set priority class names for Rook components for the list of key value pairs:

  • all: Set priority class names for MGRs, Mons, OSDs, and RBD Mirrors.
  • mgr: Set priority class names for MGRs.
  • mon: Set priority class names for Mons.
  • osd: Set priority class names for OSDs.
  • rbdmirror: Set priority class names for RBD Mirrors.

The specific component keys will act as overrides to all.

Samples

Here are several samples for configuring Ceph clusters. Each of the samples must also include the namespace and corresponding access granted for management by the Ceph operator. See the common cluster resources below.

Storage configuration: All devices

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    image: ceph/ceph:v14.2.5
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: true
  dashboard:
    enabled: true
  # cluster level storage configuration and selection
  storage:
    useAllNodes: true
    useAllDevices: true
    deviceFilter:
    config:
      metadataDevice:
      databaseSizeMB: "1024" # this value can be removed for environments with normal sized disks (100 GB or larger)
      journalSizeMB: "1024"  # this value can be removed for environments with normal sized disks (20 GB or larger)
      osdsPerDevice: "1"

Storage Configuration: Specific devices

Individual nodes and their config can be specified so that only the named nodes below will be used as storage resources. Each node's 'name' field should match their 'kubernetes.io/hostname' label.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    image: ceph/ceph:v14.2.5
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: true
  dashboard:
    enabled: true
  # cluster level storage configuration and selection
  storage:
    useAllNodes: false
    useAllDevices: false
    deviceFilter:
    config:
      metadataDevice:
      databaseSizeMB: "1024" # this value can be removed for environments with normal sized disks (100 GB or larger)
      journalSizeMB: "1024"  # this value can be removed for environments with normal sized disks (20 GB or larger)
    nodes:
    - name: "172.17.4.101"
      directories:         # specific directories to use for storage can be specified for each node
      - path: "/rook/storage-dir"
    - name: "172.17.4.201"
      devices:             # specific devices to use for storage can be specified for each node
      - name: "sdb"
      - name: "sdc"
      config:         # configuration can be specified at the node level which overrides the cluster level config
        storeType: bluestore
    - name: "172.17.4.301"
      deviceFilter: "^sd."

Storage Configuration: Cluster wide Directories

This example is based on the Storage Configuration: Specific devices. Individual nodes can override the cluster wide specified directories list.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    image: ceph/ceph:v14.2.5
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: true
  dashboard:
    enabled: true
  # cluster level storage configuration and selection
  storage:
    useAllNodes: false
    useAllDevices: false
    config:
      databaseSizeMB: "1024" # this value can be removed for environments with normal sized disks (100 GB or larger)
      journalSizeMB: "1024"  # this value can be removed for environments with normal sized disks (20 GB or larger)
    directories:
    - path: "/rook/storage-dir"
    nodes:
    - name: "172.17.4.101"
      directories: # specific directories to use for storage can be specified for each node
      # overrides the above `directories` values for this node
      - path: "/rook/my-node-storage-dir"
    - name: "172.17.4.201"

Node Affinity

To control where various services will be scheduled by kubernetes, use the placement configuration sections below. The example under 'all' would have all services scheduled on kubernetes nodes labeled with 'role=storage-node' and tolerate taints with a key of 'storage-node'.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    image: ceph/ceph:v14.2.5
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: true
  # enable the ceph dashboard for viewing cluster status
  dashboard:
    enabled: true
  placement:
    all:
      nodeAffinity:
        requiredDuringSchedulingIgnoredDuringExecution:
          nodeSelectorTerms:
          - matchExpressions:
            - key: role
              operator: In
              values:
              - storage-node
      tolerations:
      - key: storage-node
        operator: Exists
    mgr:
      nodeAffinity:
      tolerations:
    mon:
      nodeAffinity:
      tolerations:
    osd:
      nodeAffinity:
      tolerations:

Resource Requests/Limits

To control how many resources the Rook components can request/use, you can set requests and limits in Kubernetes for them. You can override these requests/limits for OSDs per node when using useAllNodes: false in the node item in the nodes list.

WARNING: Before setting resource requests/limits, please take a look at the Ceph documentation for recommendations for each component: Ceph - Hardware Recommendations.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    image: ceph/ceph:v14.2.5
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: true
  # enable the ceph dashboard for viewing cluster status
  dashboard:
    enabled: true
  # cluster level resource requests/limits configuration
  resources:
  storage:
    useAllNodes: false
    nodes:
    - name: "172.17.4.201"
      resources:
        limits:
          cpu: "2"
          memory: "4096Mi"
        requests:
          cpu: "2"
          memory: "4096Mi"

OSD Topology

The topology of the cluster is important in production environments where you want your data spread across failure domains. The topology can be controlled by adding labels to the nodes. When the labels are found on a node at first OSD deployment, Rook will add them to the desired level in the CRUSH map.

The complete list of labels in hierarchy order from highest to lowest is:

failure-domain.beta.kubernetes.io/region
failure-domain.beta.kubernetes.io/zone
topology.rook.io/datacenter
topology.rook.io/room
topology.rook.io/pod
topology.rook.io/pdu
topology.rook.io/row
topology.rook.io/rack
topology.rook.io/chassis

For example, if the following labels were added to a node:

kubectl label node mynode failure-domain.beta.kubernetes.io/zone=zone1
kubectl label node mynode topology.rook.io/rack=rack1

These labels would result in the following hierarchy for OSDs on that node (this command can be run in the Rook toolbox):

[root@mynode /]# ceph osd tree
ID CLASS WEIGHT  TYPE NAME                 STATUS REWEIGHT PRI-AFF
-1       0.01358 root default
-5       0.01358     zone zone1
-4       0.01358         rack rack1
-3       0.01358             host mynode
 0   hdd 0.00679                 osd.0         up  1.00000 1.00000
 1   hdd 0.00679                 osd.1         up  1.00000 1.00000

Note that the host is added automatically to the hierarchy by Rook. The host cannot be specified with a topology label. All topology labels are optional.

HINT When setting the node labels prior to CephCluster creation, these settings take immediate effect. However, applying this to an already deployed CephCluster requires removing each node from the cluster first and then re-adding it with new configuration to take effect. Do this node by node to keep your data safe! Check the result with ceph osd tree from the Rook Toolbox. The OSD tree should display the hierarchy for the nodes that already have been re-added.

To utilize the failureDomain based on the node labels, specify the corresponding option in the CephBlockPool

apiVersion: ceph.rook.io/v1
kind: CephBlockPool
metadata:
  name: replicapool
  namespace: rook-ceph
spec:
  failureDomain: rack  # this matches the topology labels on nodes
  replicated:
    size: 3

This configuration will split the replication of volumes across unique racks in the data center setup.

Using PVC storage for monitors

In the CRD specification below three monitors are created each using a 10Gi PVC created by Rook using the local-storage storage class.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    image: ceph/ceph:v14.2.5
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: false
    volumeClaimTemplate:
      spec:
        storageClassName: local-storage
        resources:
          requests:
            storage: 10Gi
  dashboard:
    enabled: true
  storage:
    useAllNodes: true
    useAllDevices: true
    deviceFilter:
    config:
      metadataDevice:
      databaseSizeMB: "1024" # this value can be removed for environments with normal sized disks (100 GB or larger)
      journalSizeMB: "1024"  # this value can be removed for environments with normal sized disks (20 GB or larger)
      osdsPerDevice: "1"

Using StorageClassDeviceSets

In the CRD specification below, 3 OSDs (having specific placement and resource values) and 3 mons with each using a 10Gi PVC, are created by Rook using the local-storage storage class.

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
    allowMultiplePerNode: false
    volumeClaimTemplate:
      spec:
        storageClassName: local-storage
        resources:
          requests:
            storage: 10Gi
  cephVersion:
    image: ceph/ceph:v14.2.5
    allowUnsupported: false
  dashboard:
    enabled: true
  network:
    hostNetwork: false
  storage:
    storageClassDeviceSets:
    - name: set1
      count: 3
      portable: false
      tuneSlowDeviceClass: false
      resources:
        limits:
          cpu: "500m"
          memory: "4Gi"
        requests:
          cpu: "500m"
          memory: "4Gi"
      placement:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchExpressions:
                - key: "rook.io/cluster"
                  operator: In
                  values:
                    - cluster1
                topologyKey: "failure-domain.beta.kubernetes.io/zone"
      volumeClaimTemplates:
      - metadata:
          name: data
        spec:
          resources:
            requests:
              storage: 10Gi
          storageClassName: local-storage
          volumeMode: Block
          accessModes:
            - ReadWriteOnce

External cluster

The minimum supported Ceph version for the External Cluster is Luminous 12.2.x.

The features available from the external cluster will vary depending on the version of Ceph. The following table shows the minimum version of Ceph for some of the features:

FEATURE CEPH VERSION
Dynamic provisioning RBD 12.2.X
Configure extra CRDs (object, file, nfs)1 13.2.3
Dynamic provisioning CephFS 14.2.3

Pre-requisites

In order to configure an external Ceph cluster with Rook, we need to inject some information in order to connect to that cluster. You can use the cluster/examples/kubernetes/ceph/import-external-cluster.sh script to achieve that. The script will look for the following populated environment variables:

  • NAMESPACE: the namespace where the configmap and secrets should be injected
  • ROOK_EXTERNAL_FSID: the fsid of the external Ceph cluster, it can be retrieved via the ceph fsid command
  • ROOK_EXTERNAL_ADMIN_SECRET: the external Ceph cluster admin secret key, it can be retrieved via the ceph auth get-key client.admin command
  • ROOK_EXTERNAL_CEPH_MON_DATA: is a common-separated list of running monitors IP address along with their ports, e.g: a=172.17.0.4:6789,b=172.17.0.5:6789,c=172.17.0.6:6789. You don't need to specify all the monitors, you can simply pass one and the Operator will discover the rest. The name of the monitor is the name that appears in the ceph status output.

Example:

export NAMESPACE=rook-ceph-external
export ROOK_EXTERNAL_FSID=3240b4aa-ddbc-42ee-98ba-4ea7b2a61514
export ROOK_EXTERNAL_ADMIN_SECRET=AQC6Ylxdja+NDBAAB7qy9MEAr4VLLq4dCIvxtg==
export ROOK_EXTERNAL_CEPH_MON_DATA=a=172.17.0.4:6789

Then you can simply execute the script like this:

bash cluster/examples/kubernetes/ceph/import-external-cluster.sh

CephCluster example

Assuming the above section has successfully completed, here is a CR example:

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph-external
  namespace: rook-ceph-external
spec:
  external:
    enable: true
  dataDirHostPath: /var/lib/rook
  # providing an image is optional, do this if you want to create other CRs (rgw, mds, nfs)
  cephVersion:
    image: ceph/ceph:v14.2.5 # MUST match external cluster version

Choose the namespace carefully, if you have an existing cluster managed by Rook, you have likely already injected common.yaml. Additionally, you now need to inject common-external.yaml too.

You can now create it like this:

kubectl create -f cluster/examples/kubernetes/ceph/cluster-external.yaml

If the previous section has not been completed, the Rook Operator will still acknowledge the CR creation but will wait forever to receive connection information.

WARNING: If no cluster is managed by the current Rook Operator, you need to inject common.yaml, then modify cluster-external.yaml and specify rook-ceph as namespace.

Footnotes

  1. Configure an object store, shared filesystem, or NFS resources in the local cluster to connect to the external Ceph cluster ↩