文件系统存储（也称为共享文件系统）能够以读写权限挂载到多个 Pod 中，这非常有利于应用使用共享存储，例如 FTP、Web、共享存储服务等。

创建文件系统

创建文件系统需要通过 CephFilesystem CRD 指定 metadata 池和 data 池以及 metadata server。

创建文件系统的示例：

apiVersion: ceph.rook.io/v1
kind: CephFilesystem
metadata:
  name: myfs
  namespace: rook-ceph
spec:
  metadataPool:
    replicated:
      size: 3
  dataPools:
    - name: myfs
      replicated:
        size: 3
  preserveFilesystemOnDelete: true
  metadataServer:
    activeCount: 1
    activeStandby: true

应用然后验证：

[vagrant@master01 examples]$ kubectl apply -f myfs.yaml 
cephfilesystem.ceph.rook.io/myfs created
[vagrant@master01 examples]$ kubectl -n rook-ceph get pod -l app=rook-ceph-mds
NAME                                   READY   STATUS    RESTARTS   AGE
rook-ceph-mds-myfs-a-5949f8b48-nn9cm   2/2     Running   0          18s
rook-ceph-mds-myfs-b-fd5c79f5d-2sgwq   2/2     Running   0          17s

在 ToolBox 中进行验证：

[vagrant@master01 examples]$ kubectl exec -it rook-ceph-tools-66b77b8df5-x97q4 -n rook-ceph -- /bin/ceph status
  cluster:
    id:     f8bdb7b9-12c8-4814-b4a2-6122366ddd1a
    health: HEALTH_WARN
            1 daemons have recently crashed

  services:
    mon: 3 daemons, quorum a,b,c (age 8m)
    mgr: a(active, since 6m), standbys: b
    mds: 1/1 daemons up, 1 hot standby
    osd: 3 osds: 3 up (since 7m), 3 in (since 4w)

  data:
    volumes: 1/1 healthy
    pools:   7 pools, 177 pgs
    objects: 32 objects, 463 KiB
    usage:   82 MiB used, 60 GiB / 60 GiB avail
    pgs:     177 active+clean

  io:
    client:   973 B/s rd, 1 op/s rd, 0 op/s wr

  progress:


[vagrant@master01 examples]$ kubectl exec -it rook-ceph-tools-66b77b8df5-x97q4 -n rook-ceph -- /bin/ceph fs ls
name: myfs, metadata pool: myfs-metadata, data pools: [myfs-replicated ]

创建存储类

创建使用 myfs 文件系统的存储类，示例定义：

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: rook-cephfs
# Change "rook-ceph" provisioner prefix to match the operator namespace if needed
provisioner: rook-ceph.cephfs.csi.ceph.com
parameters:
  # clusterID is the namespace where the rook cluster is running
  # If you change this namespace, also change the namespace below where the secret namespaces are defined
  clusterID: rook-ceph

  # CephFS filesystem name into which the volume shall be created
  fsName: myfs

  # Ceph pool into which the volume shall be created
  # Required for provisionVolume: "true"
  pool: myfs-replicated

  # The secrets contain Ceph admin credentials. These are generated automatically by the operator
  # in the same namespace as the cluster.
  csi.storage.k8s.io/provisioner-secret-name: rook-csi-cephfs-provisioner
  csi.storage.k8s.io/provisioner-secret-namespace: rook-ceph
  csi.storage.k8s.io/controller-expand-secret-name: rook-csi-cephfs-provisioner
  csi.storage.k8s.io/controller-expand-secret-namespace: rook-ceph
  csi.storage.k8s.io/node-stage-secret-name: rook-csi-cephfs-node
  csi.storage.k8s.io/node-stage-secret-namespace: rook-ceph

reclaimPolicy: Delete

应用：

[vagrant@master01 examples]$ kubectl apply -f storageclass-myfs.yaml 
storageclass.storage.k8s.io/rook-cephfs created
[vagrant@master01 examples]$ kubectl get sc
NAME                 PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
rook-ceph-block      rook-ceph.rbd.csi.ceph.com      Delete          Immediate           true                   6h56m
rook-ceph-block-ec   rook-ceph.rbd.csi.ceph.com      Delete          Immediate           true                   6h42m
rook-cephfs          rook-ceph.cephfs.csi.ceph.com   Delete          Immediate           false                  3s

使用文件系统存储类

首先创建一个使用 rook-cephfs 的 PVC：

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nginx-pvc
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 1Gi
  storageClassName: rook-cephfs

应用并检查：

[vagrant@master01 rook-ceph]$ kubectl apply -f nginx-pvc.yaml 
persistentvolumeclaim/nginx-pvc created
[vagrant@master01 rook-ceph]$ kubectl get pvc -n cephfs-demo
NAME        STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
nginx-pvc   Bound    pvc-a5fea40e-9055-4304-ab8b-782082184a3a   1Gi        RWX            rook-cephfs    <unset>                 8s

创建一个 Nginx 应用，并使用 nginx-pvc ：

apiVersion: v1
kind: Pod
metadata:
  name: test-cephfs-pod
  namespace: cephfs-demo
spec:
  volumes:
    - name: nginx-pvc
      persistentVolumeClaim:
        claimName: nginx-pvc
  containers:
    - name: nginx
      image: nginx
      ports:
        - containerPort: 80
          name: "http-server"
      volumeMounts:
        - mountPath: "/usr/share/nginx/html"
          name: nginx-pvc

应用并验证：

[vagrant@master01 rook-ceph]$ kubectl apply -f test-cephfs-pod.yaml 
pod/test-cephfs-pod created

[vagrant@master01 rook-ceph]$ kubectl get pods -n cephfs-demo
NAME              READY   STATUS    RESTARTS   AGE
test-cephfs-pod   1/1     Running   0          98s
[vagrant@master01 rook-ceph]$ 
[vagrant@master01 rook-ceph]$ kubectl -n cephfs-demo exec -it test-cephfs-pod -- /bin/mount | grep nginx
10.101.27.111:6789,10.106.190.243:6789,10.107.18.191:6789:/volumes/csi/csi-vol-0435565e-561a-45d6-99d6-2ce34f5b59c0/a840ec39-e187-4095-b8c9-7ccb1c792626 on /usr/share/nginx/html type ceph (rw,relatime,name=csi-cephfs-node,secret=<hidden>,fsid=00000000-0000-0000-0000-000000000000,acl,mds_namespace=myfs)