Ceph

PLEASE NOTE: This document applies to v1.0 version and not to the latest stable release v1.9

Ceph Storage Quickstart

This guide will walk you through the basic setup of a Ceph cluster and enable you to consume block, object, and file storage from other pods running in your cluster.

Minimum Version

Kubernetes v1.10 or higher is supported by Rook.

Prerequisites

To make sure you have a Kubernetes cluster that is ready for Rook, you can follow these instructions.

If you are using dataDirHostPath to persist rook data on kubernetes hosts, make sure your host has at least 5GB of space available on the specified path.

TL;DR

If you’re feeling lucky, a simple Rook cluster can be created with the following kubectl commands and example yaml files. For the more detailed install, skip to the next section to deploy the Rook operator.

cd cluster/examples/kubernetes/ceph
kubectl create -f common.yaml
kubectl create -f operator.yaml
kubectl create -f cluster-test.yaml

After the cluster is running, you can create block, object, or file storage to be consumed by other applications in your cluster.

Production Environments

For production environments it is required to have local storage devices attached to your nodes. In this walkthrough, the requirement of local storage devices is relaxed so you can get a cluster up and running as a “test” environment to experiment with Rook. A Ceph filestore OSD will be created in a directory instead of requiring a device. For production environments, you will want to follow the example in cluster.yaml instead of cluster-test.yaml in order to configure the devices instead of test directories. See the Ceph examples for more details.

Deploy the Rook Operator

The first step is to deploy the Rook system components, which include the Rook agent running on each node in your cluster as well as Rook operator pod. Check that you are using the example yaml files that correspond to your release of Rook. For more options, see the examples documentation.

cd cluster/examples/kubernetes/ceph
kubectl create -f common.yaml
kubectl create -f operator.yaml

# verify the rook-ceph-operator, rook-ceph-agent, and rook-discover pods are in the `Running` state before proceeding
kubectl -n rook-ceph get pod

You can also deploy the operator with the Rook Helm Chart.

Create a Rook Ceph Cluster

Now that the Rook operator, agent, and discover pods are running, we can create the Rook Ceph cluster. For the cluster to survive reboots, make sure you set the dataDirHostPath property that is valid for your hosts. For more settings, see the documentation on configuring the cluster.

Save the cluster spec as cluster-test.yaml:

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    # For the latest ceph images, see https://hub.docker.com/r/ceph/ceph/tags
    image: ceph/ceph:v14.2.1-20190430
  dataDirHostPath: /var/lib/rook
  mon:
    count: 3
  dashboard:
    enabled: true
  storage:
    useAllNodes: true
    useAllDevices: false
    # Important: Directories should only be used in pre-production environments
    directories:
    - path: /var/lib/rook

Create the cluster:

kubectl create -f cluster-test.yaml

Use kubectl to list pods in the rook-ceph namespace. You should be able to see the following pods once they are all running. The number of osd pods will depend on the number of nodes in the cluster and the number of devices and directories configured. If you did not modify the cluster-test.yaml above, it is expected that one OSD will be created per node.

$ kubectl -n rook-ceph get pod
NAME                                   READY   STATUS      RESTARTS   AGE
rook-ceph-agent-4zkg8                  1/1     Running     0          140s
rook-ceph-mgr-a-d9dcf5748-5s9ft        1/1     Running     0          77s
rook-ceph-mon-a-7d8f675889-nw5pl       1/1     Running     0          105s
rook-ceph-mon-b-856fdd5cb9-5h2qk       1/1     Running     0          94s
rook-ceph-mon-c-57545897fc-j576h       1/1     Running     0          85s
rook-ceph-operator-6c49994c4f-9csfz    1/1     Running     0          141s
rook-ceph-osd-0-7cbbbf749f-j8fsd       1/1     Running     0          23s
rook-ceph-osd-1-7f67f9646d-44p7v       1/1     Running     0          24s
rook-ceph-osd-2-6cd4b776ff-v4d68       1/1     Running     0          25s
rook-ceph-osd-prepare-node1-vx2rz      0/2     Completed   0          60s
rook-ceph-osd-prepare-node2-ab3fd      0/2     Completed   0          60s
rook-ceph-osd-prepare-node3-w4xyz      0/2     Completed   0          60s
rook-discover-dhkb8                    1/1     Running     0          140s

To verify that the cluster is in a healthy state, connect to the Rook toolbox and run the ceph status command.

All mons should be in quorum
A mgr should be active
At least one OSD should be active

If the health is not HEALTH_OK, the warnings or errors should be investigated

$ ceph status
cluster:
  id:     a0452c76-30d9-4c1a-a948-5d8405f19a7c
  health: HEALTH_OK

services:
  mon: 3 daemons, quorum a,b,c (age 3m)
  mgr: a(active, since 2m)
  osd: 3 osds: 3 up (since 1m), 3 in (since 1m)
...

If the cluster is not healthy, please refer to the Ceph common issues for more details and potential solutions.

Storage

For a walkthrough of the three types of storage exposed by Rook, see the guides for:

Block: Create block storage to be consumed by a pod
Object: Create an object store that is accessible inside or outside the Kubernetes cluster
Shared File System: Create a file system to be shared across multiple pods

Ceph Dashboard

Ceph has a dashboard in which you can view the status of your cluster. Please see the dashboard guide for more details.

Tools

We have created a toolbox container that contains the full suite of Ceph clients for debugging and troubleshooting your Rook cluster. Please see the toolbox readme for setup and usage information. Also see our advanced configuration document for helpful maintenance and tuning examples.

Monitoring

Each Rook cluster has some built in metrics collectors/exporters for monitoring with Prometheus. To learn how to set up monitoring for your Rook cluster, you can follow the steps in the monitoring guide.

Teardown

When you are done with the test cluster, see these instructions to clean up the cluster.