Overview
3.1. Persistent storage overview
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#persistent-storage-overview_understanding-persistent-storage
The OpenShift storage architecture has three primary components:
- Storage Classes
- Persistent Volumes
- Persistent Volume Claims
Persistent Volume Claims (pvc)
The project defines pvc with following
- Storage Size: [G|Gi...]
- Storage Class:
- Access Mode: [ReadWriteMany|ReadWriteOnce|ReadOnlyMany]
- Volume Mode: [Filesystem|Block|Object]
Persistent Volume (pv)
4.11. Persistent storage using NFS
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#persistent-storage-using-nfs
Example Persistent Volume
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv0001
spec:
capacity:
storage: 5Gi
storageClassName: nfs-storage
accessModes:
- ReadWriteOnce
volumeMode: Filesystem
nfs:
path: /tmp
server: 172.17.0.2
persistentVolumeReclaimPolicy: Retain
This persistent volume uses the NFS volume plug-in. The nfs section defines parameters that the NFS volume plug-in requires to mount the volume on a node. This section includes sensitive NFS configuration information.
Provisioning and Binding Persistent Volumes
- Install a storage operator
- Write and use Ansible Playbooks
Persistent Volume Reclaim Policy
3.2.6. Reclaim policy for persistent volumes
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#reclaiming_understanding-persistent-storage
- Delete: reclaim policy deletes both the PersistentVolume object from OpenShift Container Platform and the associated storage asset in external infrastructure, such as AWS EBS or VMware vSphere. All dynamically-provisioned persistent volumes use a Delete reclaim policy.
- Retain: Reclaim policy allows manual reclamation of the resource for those volume plug-ins that support it.
- Recycle: Reclaim policy recycles the volume back into the pool of unbound persistent volumes once it is released from its claim.
Supported access modes for PVs
Table 3.2. Supported access modes for PVs
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#pv-access-modes_understanding-persistent-storage
Available dynamic provisioning plug-ins
7.2. Available dynamic provisioning plug-ins
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#available-plug-ins_dynamic-provisioning
Setting a Default Storage Class
7.3.2. Storage class annotations
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#storage-class-annotations_dynamic-provisioning
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
annotations:
storageclass.kubernetes.io/is-default-class: "true"
Restricting Access to Storage Resources
5.1.1. Resources managed by quotas
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/applications/index#quotas-resources-managed_quotas-setting-per-project
| requests.storage |
The sum of storage requests across all persistent volume claims in any state cannot exceed this value. |
| persistentvolumeclaims |
The total number of persistent volume claims that can exist in the project. |
| <storage-class-name>.storageclass.storage.k8s.io/requests.storage |
The sum of storage requests across all persistent volume claims in any state that have a matching storage class, cannot exceed this value. |
| <storage-class-name>.storageclass.storage.k8s.io/persistentvolumeclaims |
The total number of persistent volume claims with a matching storage class that can exist in the project. |
Block Volume
3.5.1. Block volume examples
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#block-volume-examples_understanding-persistent-storage
apiVersion: v1
kind: PersistentVolume
metadata:
name: block-pv
spec:
capacity:
storage: 10Gi
accessModes:
- ReadWriteOnce
volumeMode: Block 1
persistentVolumeReclaimPolicy: Retain
fc:
targetWWNs: ["50060e801049cfd1"]
lun: 0
readOnly: false
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: block-pvc
spec:
accessModes:
- ReadWriteOnce
volumeMode: Block
resources:
requests:
storage: 10Gi
---
apiVersion: v1
kind: Pod
metadata:
name: pod-with-block-volume
spec:
containers:
- name: fc-container
image: fedora:26
command: ["/bin/sh", "-c"]
args: [ "tail -f /dev/null" ]
volumeDevices:
- name: data
devicePath: /dev/xvda
volumes:
- name: data
persistentVolumeClaim:
claimName: block-pvc
Persistent storage using iSCSI
4.9. Persistent storage using iSCSI
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#persistent-storage-using-iscsi
PersistentVolume object definition
apiVersion: v1
kind: PersistentVolume
metadata:
name: iscsi-pv
spec:
capacity:
storage: 1Gi
volumeMode: Filesystem
storageClassName: iscsi-blk
accessModes:
- ReadWriteOnce
iscsi:
targetPortal: 10.0.0.1:3260
iqn: iqn.2016-04.test.com:storage.target00
lun: 0
initiatorName: iqn.2016-04.test.com:custom.iqn 1
fsType: ext4
readOnly: false
Persistent storage using local volumes
Installing the Local Storage Operator
4.10.1. Installing the Local Storage Operator
https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/html-single/storage/index#local-storage-install_persistent-storage-local
$ oc debug node/worker06 -- lsblk
...
vdb 252:16 0 20G 0 disk
$ oc adm new-project openshift-local-storage
$ OC_VERSION=$(oc version -o yaml | grep openshiftVersion | \
grep -o '[0-9]*[.][0-9]*' | head -1)
apiVersion: operators.coreos.com/v1alpha2
kind: OperatorGroup
metadata:
name: local-operator-group
namespace: openshift-local-storage
spec:
targetNamespaces:
- openshift-local-storage
---
apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
name: local-storage-operator
namespace: openshift-local-storage
spec:
channel: "${OC_VERSION}"
installPlanApproval: Automatic 1
name: local-storage-operator
source: redhat-operators
sourceNamespace: openshift-marketplace
$ oc apply -f openshift-local-storage.yaml
Verify installation
$ oc -n openshift-local-storage get pods
$ oc get csv -n openshift-local-storage
NAME DISPLAY VERSION REPLACES PHASE
local-storage-operator.4.2.26-202003230335 Local Storage 4.2.26-202003230335 Succeeded
Provisioning local volumes by using the Local Storage Operator
$ export CSV_NAME=$(oc get csv -n openshift-local-storage -o name)
$ oc get ${CSV_NAME} -o jsonpath='{.spec.customresourcedefinitions.owned[*].kind}{"\n"}'
LocalVolume LocalVolumeSet LocalVolumeDiscovery LocalVolumeDiscoveryResult
$ oc get ${CSV_NAME} -o jsonpath='{.metadata.annotations.alm-examples}{"\n"}'
[
{
"apiVersion": "local.storage.openshift.io/v1",
"kind": "LocalVolume",
"metadata": {
"name": "example"
},
"spec": {
"storageClassDevices": [
{
"devicePaths": [
"/dev/vde",
"/dev/vdf"
],
"fsType": "ext4",
"storageClassName": "foobar",
"volumeMode": "Filesystem"
}
]
}
}
...
]
apiVersion: local.storage.openshift.io/v1
kind: LocalVolume
metadata:
name: local-storage
spec:
storageClassDevices:
- devicePaths:
- /dev/vdb
fsType: ext4
storageClassName: local-blk
volumeMode: Filesystem
