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add pv protection description (#7620)

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This commit is contained in:
Yuquan Ren
2018-03-05 17:39:51 +08:00
committed by k8s-ci-robot
parent 805f2c7897
commit 90e5519a54
4 changed files with 119 additions and 5 deletions
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_data/tasks.yml
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@@ -170,7 +170,7 @@ toc:
- docs/tasks/administer-cluster/configure-multiple-schedulers.md
- docs/tasks/administer-cluster/ip-masq-agent.md
- docs/tasks/administer-cluster/dns-custom-nameservers.md
- docs/tasks/administer-cluster/pvc-protection.md
- docs/tasks/administer-cluster/storage-object-in-use-protection.md
- title: Federation - Run an App on Multiple Clusters
section:
docs/admin/authorization/rbac.md
+1
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@@ -628,6 +628,7 @@ These roles include:
* system:controller:node-controller
* system:controller:persistent-volume-binder
* system:controller:pod-garbage-collector
* system:controller:pv-protection-controller
* system:controller:pvc-protection-controller
* system:controller:replicaset-controller
* system:controller:replication-controller
docs/concepts/storage/persistent-volumes.md
+25 -2
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@@ -72,14 +72,15 @@ Once a user has a claim and that claim is bound, the bound PV belongs to the use
### Storage Object in Use Protection
{% assign for_k8s_version="v1.10" %}{% include feature-state-beta.md %}
The purpose of the Storage Object in Use Protection feature is to ensure that Persistent Volume Claims (PVCs) in active use by a pod are not removed from the system as this may result in data loss.
The purpose of the Storage Object in Use Protection feature is to ensure that Persistent Volume Claims (PVCs) in active use by a pod and Persistent Volume (PVs) that are bound to PVCs are not removed from the system as this may result in data loss.
**Note:** PVC is in active use by a pod when the pod status is `Pending` and the pod is assigned to a node or the pod status is `Running`.
{: .note}
When the [Storage Object in Use Protection beta feature](/docs/tasks/administer-cluster/pvc-protection/) is enabled, if a user deletes a PVC in active use by a pod, the PVC is not removed immediately. PVC removal is postponed until the PVC is no longer actively used by any pods.
When the [Storage Object in Use Protection beta feature](/docs/tasks/administer-cluster/storage-object-in-use-protection/) is enabled, if a user deletes a PVC in active use by a pod, the PVC is not removed immediately. PVC removal is postponed until the PVC is no longer actively used by any pods, and also if admin deletes a PV that is bound to a PVC, the PV is not removed immediately. PV removal is postponed until the PV is not bound to a PVC any more.
You can see that a PVC is protected when the PVC's status is `Terminating` and the `Finalizers` list includes `kubernetes.io/pvc-protection`:
```shell
kubectl describe pvc hostpath
Name: hostpath
@@ -94,6 +95,28 @@ Finalizers: [kubernetes.io/pvc-protection]
...
```
You can see that a PV is protected when the PV's status is `Terminating` and the `Finalizers` list includes `kubernetes.io/pv-protection` too:
```shell
kubectl describe pv task-pv-volume
Name: task-pv-volume
Labels: type=local
Annotations: <none>
Finalizers: [kubernetes.io/pv-protection]
StorageClass: standard
Status: Available
Claim:
Reclaim Policy: Delete
Access Modes: RWO
Capacity: 1Gi
Message:
Source:
Type: HostPath (bare host directory volume)
Path: /tmp/data
HostPathType:
Events: <none>
```
### Reclaiming
When a user is done with their volume, they can delete the PVC objects from the API which allows reclamation of the resource. The reclaim policy for a `PersistentVolume` tells the cluster what to do with the volume after it has been released of its claim. Currently, volumes can either be Retained, Recycled or Deleted.
docs/tasks/administer-cluster/pvc-protection.md → docs/tasks/administer-cluster/storage-object-in-use-protection.md
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@@ -8,7 +8,7 @@ title: Storage Object in Use Protection
{% capture overview %}
{% assign for_k8s_version="v1.10" %}{% include feature-state-beta.md %}
Persistent volume claims (PVCs) that are in active use by a pod can be protected from pre-mature removal.
Persistent volume claims (PVCs) that are in active use by a pod and persistent volumes (PVs) that are bound to PVCs can be protected from pre-mature removal.
{% endcapture %}
@@ -56,8 +56,9 @@ spec:
```
- Check that the PVC has the finalizer `kubernetes.io/pvc-protection` set:
```shell
$ kubectl describe pvc slzc
kubectl describe pvc slzc
Name: slzc
Namespace: default
StorageClass: slow
@@ -215,6 +216,95 @@ Warning FailedScheduling 18s (x4 over 21s) default-scheduler persistentvolum
- Wait until the pod status of both pods is `Terminated` or `Completed` (either delete the pods or wait until they finish). Afterwards, check that the PVC is removed.
## Storage Object in Use Protection feature used for PV Protection
The example below uses a `HostPath` PV.
Verification scenarios follow below.
### Scenario 1: The PV is not bound to a PVC
- Create a PV:
```yaml
kind: PersistentVolume
apiVersion: v1
metadata:
name: task-pv-volume
labels:
type: local
spec:
capacity:
storage: 1Gi
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Delete
storageClassName: standard
hostPath:
path: "/tmp/data"
```
- Check that the PV has the finalizer `kubernetes.io/pv-protection` set:
```shell
Name: task-pv-volume
Labels: type=local
Annotations: pv.kubernetes.io/bound-by-controller=yes
Finalizers: [kubernetes.io/pv-protection]
StorageClass: standard
Status: Terminating (lasts 1m)
Claim: default/task-pv-claim
Reclaim Policy: Delete
Access Modes: RWO
Capacity: 1Gi
Message:
Source:
Type: HostPath (bare host directory volume)
Path: /tmp/data
HostPathType:
Events: <none>
```
- Delete the PV and check that the PV (not bound to a PVC) is removed successfully.
### Scenario 2: The PV is bound to a PVC
- Again, create the same PV.
- Create a PVC
```yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: task-pv-claim
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
```
- Wait until the PV and PVC are bound to each other.
- Delete the PV and verify that the PV is not removed but its status is `Terminating`:
```shell
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
task-pv-volume 1Gi RWO Delete Terminating default/task-pv-claim standard 59s
```
- Delete the PVC and verify that the PV is removed too.
```shell
kubectl delete pvc task-pv-claim
persistentvolumeclaim "task-pv-claim" deleted
$ kubectl get pvc
No resources found.
$ kubectl get pv
No resources found.
```
{% endcapture %}
{% capture discussion %}