Chapter 2. Migration Toolkit for Containers release notes

The Migration Toolkit for Containers (MTC) enables you to migrate application workloads between OpenShift Container Platform clusters at the granularity of a namespace.

You can migrate from OpenShift Container Platform 3 to 4.8 and between OpenShift Container Platform 4 clusters.

MTC provides a web console and an API, based on Kubernetes custom resources, to help you control the migration and minimize application downtime.

2.1. Migration Toolkit for Containers 1.6 release notes

The release notes for Migration Toolkit for Containers (MTC) version 1.6 describe new features and enhancements, deprecated features, and known issues.

2.1.1. New features and enhancements

This release has the following new features and enhancements:

  • State migration: You can perform repeatable, state-only migrations by selecting specific persistent volume claims (PVCs).
  • "New operator version available" notification: The Clusters page of the MTC web console displays a notification when a new Migration Toolkit for Containers Operator is available.

2.1.2. Deprecated features

The following features are deprecated:

  • MTC version 1.4 is no longer supported.

2.1.3. Known issues

This release has the following known issues:

  • On OpenShift Container Platform 3.10, the MigrationController pod takes too long to restart. The Bugzilla report contains a workaround. (BZ#1986796)
  • Stage pods fail during direct volume migration from a classic OpenShift Container Platform source cluster on IBM Cloud. The IBM block storage plugin does not allow the same volume to be mounted on multiple pods of the same node. As a result, the PVCs cannot be mounted on the Rsync pods and on the application pods simultaneously. To resolve this issue, stop the application pods before migration. (BZ#1887526)
  • MigPlan custom resource does not display a warning when an AWS gp2 PVC has no available space. (BZ#1963927)
  • Block storage for IBM Cloud must be in the same availability zone. See the IBM FAQ for block storage for virtual private cloud.

2.2. Migration Toolkit for Containers 1.5 release notes

The release notes for Migration Toolkit for Containers (MTC) version 1.5 describe new features, enhancements, and known issues.

2.2.1. New features and enhancements

This release has the following new features and enhancements:

  • The Migration resource tree on the Migration details page of the web console has been enhanced with additional resources, Kubernetes events, and live status information for monitoring and debugging migrations.
  • The web console can support hundreds of migration plans.
  • A source namespace can be mapped to a different target namespace in a migration plan. Previously, the source namespace was mapped to a target namespace with the same name.
  • Hook phases with status information are displayed in the web console during a migration.
  • The number of Rsync retry attempts is displayed in the web console during direct volume migration.
  • Persistent volume (PV) resizing can be enabled for direct volume migration to ensure that the target cluster does not run out of disk space.
  • The threshold that triggers PV resizing is configurable. Previously, PV resizing occurred when the disk usage exceeded 97%.
  • Velero has been updated to version 1.6, which provides numerous fixes and enhancements.
  • Cached Kubernetes clients can be enabled to provide improved performance.

2.2.2. Deprecated features

The following features are deprecated:

  • MTC versions 1.2 and 1.3 are no longer supported.
  • The procedure for updating deprecated APIs has been removed from the troubleshooting section of the documentation because the oc convert command is deprecated.

2.2.3. Known issues

This release has the following known issues:

  • Microsoft Azure storage is unavailable if you create more than 400 migration plans. The MigStorage custom resource displays the following message: The request is being throttled as the limit has been reached for operation type. (BZ#1977226)
  • If a migration fails, the migration plan does not retain custom persistent volume (PV) settings for quiesced pods. You must manually roll back the migration, delete the migration plan, and create a new migration plan with your PV settings. (BZ#1784899)
  • PV resizing does not work as expected for AWS gp2 storage unless the pv_resizing_threshold is 42% or greater. (BZ#1973148)
  • PV resizing does not work with OpenShift Container Platform 3.7 and 3.9 source clusters in the following scenarios:

    • The application was installed after MTC was installed.
    • An application pod was rescheduled on a different node after MTC was installed.

      OpenShift Container Platform 3.7 and 3.9 do not support the Mount Propagation feature that enables Velero to mount PVs automatically in the Restic pod. The MigAnalytic custom resource (CR) fails to collect PV data from the Restic pod and reports the resources as 0. The MigPlan CR displays a status similar to the following:

      Example output

      status:
        conditions:
        - category: Warn
          lastTransitionTime: 2021-07-15T04:11:44Z
          message: Failed gathering extended PV usage information for PVs [nginx-logs nginx-html], please see MigAnalytic openshift-migration/ocp-24706-basicvolmig-migplan-1626319591-szwd6 for details
          reason: FailedRunningDf
          status: "True"
          type: ExtendedPVAnalysisFailed

      To enable PV resizing, you can manually restart the Restic daemonset on the source cluster or restart the Restic pods on the same nodes as the application. If you do not restart Restic, you can run the direct volume migration without PV resizing. (BZ#1982729)

2.2.4. Technical changes

This release has the following technical changes:

  • The legacy Migration Toolkit for Containers Operator version 1.5.1 is installed manually on OpenShift Container Platform versions 3.7 to 4.5.
  • The Migration Toolkit for Containers Operator version 1.5.1 is installed on OpenShift Container Platform versions 4.6 and later by using the Operator Lifecycle Manager.

2.3. Migration Toolkit for Containers 1.4 release notes

The release notes for Migration Toolkit for Containers (MTC) version 1.4 describe new features, enhancements, and known issues.

2.3.1. Known issues

  • MTC 1.4.6 cannot be deployed on OpenShift Container Platform 3.9 (BZ#1981794) or 3.10 (BZ#1981537).