Use UFS in UK8S

This document introduces how to use UFS as the underlying storage support for K8S in UK8S clusters. UFS is shared storage and can serve multiple Pods at the same time.

Prerequisites

Purchase a UFS instance and set up the mount point on the UFS product page. After the operation is completed, you will get the UFS mount address and directory, similar to 10.19.255.192:/ .
Cluster nodes install nfs-utils, using the command ”yum install -y nfs-utils”. UK8S nodes after May 1, 2019 are installed with nfs-utils by default.
UFS and UK8S clusters must be in the same VPC, otherwise the file system cannot be successfully mounted.

Create PV

You need to manually create persistent storage volumes within the cluster. There are two types of yaml examples as follows:

UFS Capacity


apiVersion: v1
kind: PersistentVolume
metadata:
  name: ufspv4
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  nfs:
    path: /
    server: 10.19.255.12  # Please modify to your UFS mount address
  mountOptions:
    - nolock
    - nfsvers=4.0    # Must be consistent with the UFS protocol created

UFS SSD Performance


apiVersion: v1
kind: PersistentVolume
metadata:
  name: ufspv4
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  nfs:
    path: /
    server: 10.9.136.11   # Please modify to your UFS mount address
  mountOptions:
    - nolock
    - nfsvers=4.0  # Must be consistent with the UFS protocol created

yaml key fields:

spec.nfs

spec.nfs.path Fill in the path of the UFS mount point here. Create PV through NFS, do not support automatic creation of subdirectories, you can pre-create a subdirectory.

spec.nfs.server Fill in the UFS mount address here

Create pv:


# kubectl  apply -f ufspv.yml 
persistentvolume/ufspv created

Create PVC

yaml example is as follows:


apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: ufsclaim
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 8Gi

After creating the PVC, you can find that PV and PVC are already bound.


# kubectl  get pv ufspv
NAME   CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM              STORAGECLASS   REASON   AGE
ufspv   8Gi        RWX            Retain           Bound    default/ufsclaim

Mount UFS in Pod


apiVersion: v1
kind: Pod
metadata:
  name: myufspod
spec:
  containers:
    - name: myfrontend
      image: uhub.surfercloud.com/wxyz/uk8s-helloworld:1.8
      volumeMounts:
      - mountPath: "/var/www/html"
        name: mypd
  volumes:
  - name: mypd
    persistentVolumeClaim:
      claimName: ufsclaim

After the Pod is created, we can use the ”kubectl exec” command to enter the container, and execute the df command to check whether the pod is mounted to the UFS.


# df -h
Filesystem                   Size  Used Avail Use% Mounted on
...
10.19.255.192:/ufs-w4wmpkev  1.0T     0  1.0T   0% /var/lib/kubelet/pods/c800f8a7-5c38-11e9-8aae-525400fa7819/volumes/kubernetes.io~nfs/ufs
...