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.

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   cephVersion:
  8.     # see the "Cluster Settings" section below for more details on which image of ceph to run
  9.     image: ceph/ceph:v14.2.9
  10.   dataDirHostPath: /var/lib/rook
  11.   mon:
  12.     count: 3
  13.     allowMultiplePerNode: true
  14.   storage:
  15.     useAllNodes: true
  16.     useAllDevices: true

PVC-based Cluster

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

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   cephVersion:
  8.     # see the "Cluster Settings" section below for more details on which image of ceph to run
  9.     image: ceph/ceph:v14.2.9
  10.   dataDirHostPath: /var/lib/rook
  11.   mon:
  12.     count: 3
  13.     volumeClaimTemplate:
  14.       spec:
  15.         storageClassName: local-storage
  16.         resources:
  17.           requests:
  18.             storage: 10Gi
  19.   storage:
  20.    storageClassDeviceSets:
  21.     - name: set1
  22.       count: 3
  23.       portable: false
  24.       tuneSlowDeviceClass: false
  25.       volumeClaimTemplates:
  26.       - metadata:
  27.           name: data
  28.         spec:
  29.           resources:
  30.             requests:
  31.               storage: 10Gi
  32.           # IMPORTANT: Change the storage class depending on your environment (e.g. local-storage, gp2)
  33.           storageClassName: local-storage
  34.           volumeMode: Block
  35.           accessModes:
  36.             - ReadWriteOnce

For a more advanced scenario, such as adding a dedicated device you can refer to the dedicated metadata device for OSD on PVC section.

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 nautilus and octopus are supported. Future versions such as pacific 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.
  • continueUpgradeAfterChecksEvenIfNotHealthy: if set to true Rook will continue the OSD daemon upgrade process even if the PGs are not clean, or continue with the MDS upgrade even the file system is not healthy.
  • 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
  • monitoring: Settings for monitoring Ceph using Prometheus. To enable monitoring on your cluster see the monitoring guide.
    • enabled: Whether to enable prometheus based monitoring for this cluster
    • rulesNamespace: Namespace to deploy prometheusRule. If empty, namespace of the cluster will be used. Recommended:
      • If you have a single Rook Ceph cluster, set the rulesNamespace to the same namespace as the cluster or keep it empty.
      • If you have multiple Rook Ceph clusters in the same Kubernetes cluster, choose the same namespace to set rulesNamespace for all the clusters (ideally, namespace with prometheus deployed). Otherwise, you will get duplicate alerts with duplicate alert definitions.
  • network: For the network settings for the cluster, refer to the network configuration settings
  • 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.
  • crashCollector: The settings for crash collector daemon(s).
    • disable: is set to true, the crash collector will not run on any node where a Ceph daemon runs
  • 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. 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.
  • cleanupPolicy: The section for confirming that cluster data should be forcibly deleted. The cleanupPolicy should only be added to the cluster when the cluster is about to be deleted. After any field of the cleanup policy is set, Rook will stop configuring the cluster as if the cluster is about to be destroyed in order to prevent these settings from being deployed unintentionally.
    • deleteDataDirOnHosts: If yes-really-destroy-data the operator will automatically delete the hostpath of cluster nodes when a delete cephcluster command is issued. Only yes-really-destroy-data and an empty string are valid values for this field.

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.

TAGMEANING
vRELNUMLatest release in this series (e.g., v14 = Nautilus)
vRELNUM.YLatest stable release in this stable series (e.g., v14.2)
vRELNUM.Y.ZA specific release (e.g., v14.2.5)
vRELNUM.Y.Z-YYYYMMDDA 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:

  1. mgr:
  2.   modules:
  3.   - name: <name of the module>
  4.     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

Network Configuration Settings

If not specified, the default SDN will be used. Configure the network that will be enabled for the cluster and services.

  • provider: Specifies the network provider that will be used to connect the network interface. You can choose between host, and multus.
  • selectors: List the network selector(s) that will be used associated by a key.

Host Networking

To use host networking, set provider: host.

Multus (EXPERIMENTAL)

Rook has experimental support for Multus.

The selector keys are required to be public and cluster where each represent:

  • public: client communications with the cluster (reads/writes)
  • cluster: internal Ceph replication network

If you want to learn more, please read Ceph Networking reference.

Based on the configuration, the operator will do the following:

  1. if only the public selector is specified both communication and replication will happen on that network
  2. if both public and cluster selectors are specified the first one will run the communication network and the second the replication network

In order to work, each selector value must match a NetworkAttachmentDefinition object name in Multus. For example, you can do:

  • public: “my-public-storage-network”
  • cluster: “my-replication-storage-network”

For multus network provider, an already working cluster with Multus networking is required. Network attachment definition that later will be attached to the cluster needs to be created before the Cluster CRD. If Rook cannot find the provided Network attachment definition it will fail running the Ceph OSD pods. You can add the Multus network attachment selection annotation selecting the created network attachment definition on selectors.

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. 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/partitions will be used. 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), or full udev path (e.g. /dev/disk/by-id/ata-ST4000DM004-XXXX - this will not change after reboots).
    • config: Device-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.

    The syntax is the same as for other placement configuration. It supports nodeAffinity, podAffinity, podAntiAffinity and tolerations keys.

    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: bluestore, the underlying storage format to use for each OSD. The default is set dynamically to bluestore for devices and is the only supported format at this point.
  • 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.
  • 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, 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).

NOTE: Placement of OSD pods is controlled using the Storage Class Device Set, not the general placement configuration.

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.

If you use labelSelector for osd pods, you must write two rules both for rook-ceph-osd and rook-ceph-osd-prepare like the example configuration. It comes from the design that there are these two pods for an OSD. For more detail, see the osd design doc and the related issue.

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

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   cephVersion:
  8.     image: ceph/ceph:v14.2.9
  9.   dataDirHostPath: /var/lib/rook
  10.   mon:
  11.     count: 3
  12.     allowMultiplePerNode: true
  13.   dashboard:
  14.     enabled: true
  15.   # cluster level storage configuration and selection
  16.   storage:
  17.     useAllNodes: true
  18.     useAllDevices: true
  19.     deviceFilter:
  20.     config:
  21.       metadataDevice:
  22.       databaseSizeMB: "1024" # this value can be removed for environments with normal sized disks (100 GB or larger)
  23.       journalSizeMB: "1024"  # this value can be removed for environments with normal sized disks (20 GB or larger)
  24.       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.

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   cephVersion:
  8.     image: ceph/ceph:v14.2.9
  9.   dataDirHostPath: /var/lib/rook
  10.   mon:
  11.     count: 3
  12.     allowMultiplePerNode: true
  13.   dashboard:
  14.     enabled: true
  15.   # cluster level storage configuration and selection
  16.   storage:
  17.     useAllNodes: false
  18.     useAllDevices: false
  19.     deviceFilter:
  20.     config:
  21.       metadataDevice:
  22.       databaseSizeMB: "1024" # this value can be removed for environments with normal sized disks (100 GB or larger)
  23.     nodes:
  24.     - name: "172.17.4.201"
  25.       devices:             # specific devices to use for storage can be specified for each node
  26.       - name: "sdb" # Whole storage device
  27.       - name: "sdc1" # One specific partition. Should not have a file system on it.
  28.       - name: "/dev/disk/by-id/ata-ST4000DM004-XXXX" # both device name and explicit udev links are supported
  29.       config:         # configuration can be specified at the node level which overrides the cluster level config
  30.         storeType: bluestore
  31.     - name: "172.17.4.301"
  32.       deviceFilter: "^sd."

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’.

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   cephVersion:
  8.     image: ceph/ceph:v14.2.9
  9.   dataDirHostPath: /var/lib/rook
  10.   mon:
  11.     count: 3
  12.     allowMultiplePerNode: true
  13.   # enable the ceph dashboard for viewing cluster status
  14.   dashboard:
  15.     enabled: true
  16.   placement:
  17.     all:
  18.       nodeAffinity:
  19.         requiredDuringSchedulingIgnoredDuringExecution:
  20.           nodeSelectorTerms:
  21.           - matchExpressions:
  22.             - key: role
  23.               operator: In
  24.               values:
  25.               - storage-node
  26.       tolerations:
  27.       - key: storage-node
  28.         operator: Exists
  29.     mgr:
  30.       nodeAffinity:
  31.       tolerations:
  32.     mon:
  33.       nodeAffinity:
  34.       tolerations:
  35.     osd:
  36.       nodeAffinity:
  37.       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.

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   cephVersion:
  8.     image: ceph/ceph:v14.2.9
  9.   dataDirHostPath: /var/lib/rook
  10.   mon:
  11.     count: 3
  12.     allowMultiplePerNode: true
  13.   # enable the ceph dashboard for viewing cluster status
  14.   dashboard:
  15.     enabled: true
  16.   # cluster level resource requests/limits configuration
  17.   resources:
  18.   storage:
  19.     useAllNodes: false
  20.     nodes:
  21.     - name: "172.17.4.201"
  22.       resources:
  23.         limits:
  24.           cpu: "2"
  25.           memory: "4096Mi"
  26.         requests:
  27.           cpu: "2"
  28.           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:

  1. topology.kubernetes.io/region
  2. topology.kubernetes.io/zone
  3. topology.rook.io/datacenter
  4. topology.rook.io/room
  5. topology.rook.io/pod
  6. topology.rook.io/pdu
  7. topology.rook.io/row
  8. topology.rook.io/rack
  9. topology.rook.io/chassis

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

  1. kubectl label node mynode topology.kubernetes.io/zone=zone1
  2. kubectl label node mynode topology.rook.io/rack=rack1

For versions previous to K8s 1.17, use the topology key: failure-domain.beta.kubernetes.io/zone or region

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

  1. [root@mynode /]# ceph osd tree
  2. ID CLASS WEIGHT  TYPE NAME                 STATUS REWEIGHT PRI-AFF
  3. -1       0.01358 root default
  4. -5       0.01358     zone zone1
  5. -4       0.01358         rack rack1
  6. -3       0.01358             host mynode
  7.  0   hdd 0.00679                 osd.0         up  1.00000 1.00000
  8.  1   hdd 0.00679                 osd.1         up  1.00000 1.00000

Ceph requires unique names at every level in the hierarchy (CRUSH map). For example, you cannot have two racks with the same name that are in different zones. Racks in different zones must be named uniquely.

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

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephBlockPool
  3. metadata:
  4.   name: replicapool
  5.   namespace: rook-ceph
  6. spec:
  7.   failureDomain: rack  # this matches the topology labels on nodes
  8.   replicated:
  9.     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.

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   cephVersion:
  8.     image: ceph/ceph:v14.2.9
  9.   dataDirHostPath: /var/lib/rook
  10.   mon:
  11.     count: 3
  12.     allowMultiplePerNode: false
  13.     volumeClaimTemplate:
  14.       spec:
  15.         storageClassName: local-storage
  16.         resources:
  17.           requests:
  18.             storage: 10Gi
  19.   dashboard:
  20.     enabled: true
  21.   storage:
  22.     useAllNodes: true
  23.     useAllDevices: true
  24.     deviceFilter:
  25.     config:
  26.       metadataDevice:
  27.       databaseSizeMB: "1024" # this value can be removed for environments with normal sized disks (100 GB or larger)
  28.       journalSizeMB: "1024"  # this value can be removed for environments with normal sized disks (20 GB or larger)
  29.       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.

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph
  5.   namespace: rook-ceph
  6. spec:
  7.   dataDirHostPath: /var/lib/rook
  8.   mon:
  9.     count: 3
  10.     allowMultiplePerNode: false
  11.     volumeClaimTemplate:
  12.       spec:
  13.         storageClassName: local-storage
  14.         resources:
  15.           requests:
  16.             storage: 10Gi
  17.   cephVersion:
  18.     image: ceph/ceph:v14.2.9
  19.     allowUnsupported: false
  20.   dashboard:
  21.     enabled: true
  22.   network:
  23.     hostNetwork: false
  24.   storage:
  25.     storageClassDeviceSets:
  26.     - name: set1
  27.       count: 3
  28.       portable: false
  29.       tuneSlowDeviceClass: false
  30.       resources:
  31.         limits:
  32.           cpu: "500m"
  33.           memory: "4Gi"
  34.         requests:
  35.           cpu: "500m"
  36.           memory: "4Gi"
  37.       placement:
  38.         podAntiAffinity:
  39.           preferredDuringSchedulingIgnoredDuringExecution:
  40.           - weight: 100
  41.             podAffinityTerm:
  42.               labelSelector:
  43.                 matchExpressions:
  44.                 - key: "rook.io/cluster"
  45.                   operator: In
  46.                   values:
  47.                     - cluster1
  48.                 topologyKey: "topology.kubernetes.io/zone"
  49.       volumeClaimTemplates:
  50.       - metadata:
  51.           name: data
  52.         spec:
  53.           resources:
  54.             requests:
  55.               storage: 10Gi
  56.           storageClassName: local-storage
  57.           volumeMode: Block
  58.           accessModes:
  59.             - ReadWriteOnce

Dedicated metadata device for OSD on PVC

In the simplest case, Ceph OSD BlueStore consumes a single (primary) storage device. BlueStore is the engine used by the OSD to store data.

The storage device is normally used as a whole, occupying the full device that is managed directly by BlueStore. It is also possible to deploy BlueStore across additional devices such as a DB device. This device can be used for storing BlueStore’s internal metadata. BlueStore (or rather, the embedded RocksDB) will put as much metadata as it can on the DB device to improve performance. If the DB device fills up, metadata will spill back onto the primary device (where it would have been otherwise). Again, it is only helpful to provision a DB device if it is faster than the primary device.

You can have multiple volumeClaimTemplates where each might either represent a device or a metadata device. So just taking the storage section this will give something like:

  1.   storage:
  2.    storageClassDeviceSets:
  3.     - name: set1
  4.       count: 3
  5.       portable: false
  6.       tuneSlowDeviceClass: false
  7.       volumeClaimTemplates:
  8.       - metadata:
  9.           name: data
  10.         spec:
  11.           resources:
  12.             requests:
  13.               storage: 10Gi
  14.           # IMPORTANT: Change the storage class depending on your environment (e.g. local-storage, gp2)
  15.           storageClassName: gp2
  16.           volumeMode: Block
  17.           accessModes:
  18.             - ReadWriteOnce
  19.       - metadata:
  20.           name: metadata
  21.         spec:
  22.           resources:
  23.             requests:
  24.               # Find the right size https://docs.ceph.com/docs/mimic/rados/configuration/bluestore-config-ref/#sizing
  25.               storage: 5Gi
  26.           # IMPORTANT: Change the storage class depending on your environment (e.g. local-storage, gp2)
  27.           storageClassName: io1
  28.           volumeMode: Block
  29.           accessModes:
  30.             - ReadWriteOnce

NOTE: Note that Rook only supports two naming convention for a given template:

  • “data”: represents the main OSD block device, where your data are being stored
  • “metadata”: represents the metadata device used to store the Ceph Bluestore database for an OSD. It is recommended to use a faster storage class for the metadata device, with a slower device for the data. Otherwise, having a separate metadata device will not improve the performance. To determine the size of the metadata block follow the official Ceph sizing guide.

With the present configuration, each OSD will have its main block allocated a 10GB device as well a 5GB device to act as a bluestore database.

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:

FEATURECEPH VERSION
Dynamic provisioning RBD12.2.X
Configure extra CRDs (object, file, nfs)113.2.3
Dynamic provisioning CephFS14.2.3

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_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.

Now, we need to give Rook a key to connect to the cluster in order to perform various operations such as health cluster check, CSI keys management etc… It is recommended to generate keys with minimal access so the admin key does not need to be used by the external cluster. In this case, the admin key is only needed to generate the keys that will be used by the external cluster. But if the admin key is to be used by the external cluster, set the following variable:

  • ROOK_EXTERNAL_ADMIN_SECRET: OPTIONAL: the external Ceph cluster admin secret key, it can be retrieved via the ceph auth get-key client.admin command.

WARNING: If you plan to create CRs (pool, rgw, mds, nfs) in the external cluster, you MUST inject the client.admin keyring as well as injecting cluster-external-management.yaml

Example:

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

If the Ceph admin key is not provided, the following script needs to be executed on a machine that can connect to the Ceph cluster using the Ceph admin key. On that machine, run cluster/examples/kubernetes/ceph/create-external-cluster-resources.sh. The script will automatically create users and keys with the lowest possible privileges and populate the necessary environment variables for cluster/examples/kubernetes/ceph/import-external-cluster.sh to work correctly.

Finally, you can simply execute the script like this from a machine that has access to your Kubernetes cluster:

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

CephCluster example (consumer)

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

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph-external
  5.   namespace: rook-ceph-external
  6. spec:
  7.   external:
  8.     enable: true
  9.   crashCollector:
  10.     disable: true

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:

  1. 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.

CephCluster example (management)

The following CephCluster CR represents a cluster that will perform management tasks on the external cluster. It will not only act as a consumer but will also allow the deployment of other CRDs such as CephFilesystem or CephObjectStore. As mentioned above, you would need to inject the admin keyring for that.

The corresponding YAML example:

  1. apiVersion: ceph.rook.io/v1
  2. kind: CephCluster
  3. metadata:
  4.   name: rook-ceph-external
  5.   namespace: rook-ceph-external
  6. spec:
  7.   external:
  8.     enable: true
  9.   dataDirHostPath: /var/lib/rook
  10.   cephVersion:
  11.     image: ceph/ceph:v14.2.9 # Should match external cluster version
  1. Configure an object store, shared filesystem, or NFS resources in the local cluster to connect to the external Ceph cluster ↩