Ceph

PLEASE NOTE: This document applies to v1.4 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 v1.11 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.

In order to configure the Ceph storage cluster, at least one of these local storage options are required:

Raw devices (no partitions or formatted filesystems)
Raw partitions (no formatted filesystem)
PVs available from a storage class in block mode

You can confirm whether your partitions or devices are formatted filesystems with the following command.

lsblk -f
NAME                  FSTYPE      LABEL UUID                                   MOUNTPOINT
vda
└─vda1                LVM2_member       eSO50t-GkUV-YKTH-WsGq-hNJY-eKNf-3i07IB
  ├─ubuntu--vg-root   ext4              c2366f76-6e21-4f10-a8f3-6776212e2fe4   /
  └─ubuntu--vg-swap_1 swap              9492a3dc-ad75-47cd-9596-678e8cf17ff9   [SWAP]
vdb

If the FSTYPE field is not empty, there is a filesystem on top of the corresponding device. In this case, you can use vdb for Ceph and can’t use vda and its partitions.

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.

git clone --single-branch --branch v1.4.9 https://github.com/rook/rook.git
cd rook/cluster/examples/kubernetes/ceph
kubectl create -f common.yaml
kubectl create -f operator.yaml
kubectl create -f cluster.yaml

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

Cluster Environments

The Rook documentation is focused around starting Rook in a production environment. Examples are also provided to relax some settings for test environments. When creating the cluster later in this guide, consider these example cluster manifests:

cluster.yaml: Cluster settings for a production cluster running on bare metal
cluster-on-pvc.yaml: Cluster settings for a production cluster running in a dynamic cloud environment
cluster-test.yaml: Cluster settings for a test environment such as minikube.

See the Ceph examples for more details.

Deploy the Rook Operator

The first step is to deploy the Rook operator. 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 is 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 is running we can create the 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.

Create the cluster:

kubectl create -f cluster.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 configured. If you did not modify the cluster.yaml above, it is expected that one OSD will be created per node. The CSI, rook-ceph-agent, and rook-discover pods are also optional depending on your settings.

If the rook-ceph-mon, rook-ceph-mgr, or rook-ceph-osd pods are not created, please refer to the Ceph common issues for more details and potential solutions.

$ kubectl -n rook-ceph get pod
NAME                                                 READY   STATUS      RESTARTS   AGE
csi-cephfsplugin-provisioner-d77bb49c6-n5tgs         5/5     Running     0          140s
csi-cephfsplugin-provisioner-d77bb49c6-v9rvn         5/5     Running     0          140s
csi-cephfsplugin-rthrp                               3/3     Running     0          140s
csi-rbdplugin-hbsm7                                  3/3     Running     0          140s
csi-rbdplugin-provisioner-5b5cd64fd-nvk6c            6/6     Running     0          140s
csi-rbdplugin-provisioner-5b5cd64fd-q7bxl            6/6     Running     0          140s
rook-ceph-agent-4zkg8                                1/1     Running     0          140s
rook-ceph-crashcollector-minikube-5b57b7c5d4-hfldl   1/1     Running     0          105s
rook-ceph-mgr-a-64cd7cdf54-j8b5p                     1/1     Running     0          77s
rook-ceph-mon-a-694bb7987d-fp9w7                     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-85f5b946bd-s8grz                  1/1     Running     0          92m
rook-ceph-osd-0-6bb747b6c5-lnvb6                     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 Filesystem: Create a filesystem 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.