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Version: 3.1

Schedule migrations with asynchronous DR in OCP IBM Cloud

Once your source and destination clusters are paired, you need to create a schedule to migrate one or more namespaces periodically.

Create a schedule policy on your source cluster​

You have two options for creating a schedule policy:

  • Run the storkctl create migrationschedule command-line tool the along with the required flags. See Create schedule policy with storkctl topic for more information about the commands with examples, or
  • Perform the following steps on your source cluster:

To schedule the migration, you need to define a schedule policy. You can choose between two types: SchedulePolicy or NamespacedSchedulePolicy.

  • SchedulePolicy: This policy is cluster-scoped and applies to the entire cluster.
  • NamespacedSchedulePolicy: This policy is namespace-scoped and applies only to the namespace that is specified in the policy spec.
note
  • It is recommended to use an interval of at least 15 minutes.
  • If a migration is not completed within the specified time interval, Portworx will not initiate the next migration until the previous one is finished.

Perform the following steps on your source cluster to create a schedule policy:

  1. Create a spec file using one of the following methods.

    • For SchedulePolicy, create the following spec file:
    apiVersion: stork.libopenstorage.org/v1alpha1
    kind: SchedulePolicy
    metadata:
      name: <your-schedule-policy>
    policy:
      interval:
        intervalMinutes: 30

    For a list of parameters that you can use to create a schedule policy, see the Schedule Policy page.

    • For NamespacedSchedulePolicy, create the following spec file:
    apiVersion: stork.libopenstorage.org/v1alpha1
    kind: NamespacedSchedulePolicy
    metadata:
      name: <your-schedule-policy>
      namespace: <migrationnamespace>
    policy:
      interval:
        intervalMinutes: 30

    For a list of parameters that you can use to create a namespaced policy, you can use the fields described on the Schedule Policy page, replacing SchedulePolicy with NamespacedSchedulePolicy.

    • You can also use the schedule policies that are installed by default. Run the storkctl get schedulepolicy command to get the list of these policies, then specify a policy name in the next section for creating a migration schedule. You can skip the next step if you are using the default policies, as they are already applied to your cluster.

  2. Apply your policy on the source cluster:

    oc apply -f <your-schedule-policy>.yaml

  3. Verify if the policy has been created:

    storkctl get schedulepolicy <your-schedule-policy>
    NAME                      INTERVAL-MINUTES    DAILY     WEEKLY             MONTHLY
    <your-schedule-policy>          30             N/A       N/A                N/A

    The output of this command provides information about the policy, including its name and interval duration.

Create a migration schedule on your source cluster​

Once a policy has been created, you can use it to schedule migrations. This means specifying when and how migrations should occur between clusters.

note

For operators deployed from the OpenShift OperatorHub, create a migration schedule with the --exclude-resource-types flag to exclude operator-related resources.

Example: storkctl create migrationschedule -c <cluster-pair> --namespaces <namespace> <migration-schedule> --exclude-resource-types ClusterServiceVersion,operatorconditions,OperatorGroup,InstallPlan,Subscription --exclude-selectors olm.managed=true

You have two options for creating a migration schedule:

  • Run the storkctl create migrationschedule command-line tool the along with the required flags. See Create migration schedule with storkctl topic for more information about the commands with examples, or
  • Perform the following steps on your source cluster:

  1. Copy and paste the following spec into a file called migrationschedule.yaml to define the details of the migration schedule.

    • Modify the following spec to use a different migration schedule name and/or namespace.
    • Ensure that the clusterPair name is correct.
    apiVersion: stork.libopenstorage.org/v1alpha1
    kind: MigrationSchedule
    metadata:
      name: migrationschedule
      namespace: <migrationnamespace>
      annotations:
        # Add the below annotations when PX-Security is enabled on both the clusters
        #openstorage.io/auth-secret-namespace: <the namespace where the kubernetes secret holding the auth token resides>
        #openstorage.io/auth-secret-name: <the name of the kubernetes secret which holds the auth token>
    spec:
      template:
        spec:
          clusterPair: migration-cluster-pair
          includeResources: true
          startApplications: false
          includeVolumes: true
          namespaces:
          - <app-namespace1>
          - <app-namespace2>
      schedulePolicyName: <your-schedule-policy>
      suspend: false
      autoSuspend: true
    note

    • The option startApplications must be set to false in the spec. Otherwise, the first migration will start the pods on the remote cluster, and all subsequent migrations will fail because the volumes will already be in use.

    • If you are running Stork 23.2 version or later, you can set the autoSuspend to true, as shown in the above spec. In case of a disaster, this will suspend the DR migration schedules automatically on your source cluster, and you will be able to migrate your application to an active ocp cluster. If you are using an older version of Stork, refer to the Failover an application page for achieving failover for your application.

    • The auth annotations openstorage.io/auth-secret-namespace and openstorage.io/auth-secret-name must be set when PX-Security is enabled on both the source and destination cluster, as explained in the ClusterPair section.

  2. Apply your migration schedule:

oc apply -f migrationschedule.yaml

If the policy name is missing or invalid, there will be events logged against the migration schedule object. Success and failures of the migrations created by the schedule will also result in events being logged against the object. These events can be seen by running a oc describe on the object

Check your migration status on your source cluster​

After applying the migration schedule, verify its status and events.

  1. Run the following command on your source cluster to check the status of your migration:
storkctl get migration -n <migrationnamespace>
NAMESPACE                      NAME                                                                CLUSTERPAIR                STAGE   STATUS       VOLUMES   RESOURCES   CREATED               ELAPSED                          TOTAL BYTES TRANSFERRED
bidirectional-clusterpair-ns   <your-app>-migration-schedule-interval-interval-2023-08-28-015917   birectional-cluster-pair   Final   Successful   1/1       4/4         27 Aug 23 19:59 MDT   Volumes (33s) Resources (1m2s)   4096

  • The output above indicates a successful migration in the Status column. It also provides a list of migration objects along with timestamps associated with your migration.

  • You can also run the oc describe migration -n <migrationnamespace> to check details about specific migrations.

  1. Verify your application and associated resources have been migrated by running the following command on your destination cluster:

oc get all -n zookeeper


```output
NAME                      TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
service/zk-service        ClusterIP   10.xxx.xx.68   <none>        xxxx/TCP   2m13s

NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/zk         0/0     0            0           2m13s

NAME                               DESIRED   CURRENT   READY   AGE
replicaset.apps/zk-59d878d987      0         0         0       2m13s

This confirms that the respective namespace has been created and the applications (for example, Zookeeper) are installed. However, the application pods will not be running because they are running on the source cluster.

note

As part of every Migration, Stork will also migrate the Kubernetes resources associated with your applications. For a successful migration, these applications need to be in a scaled down state on the destination side so that subsequent migrations from the same schedule can run to completion. To achieve this Stork will leverage spec.replicas from most of the standard Kubernetes controllers such as Deployments, StatefulSets, and so on. However, for applications managed by an Operator an ApplicationRegistration CR needs to be created which provides Stork with the necessary information required to perform a scale down of the application. Refer to the ApplicationRegistrations page for more details.

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