# How-to Guide: Initiating a Migration

### Prerequisites

Before initiating the migration, ensure the following prerequisites are met:

1. Access to the VMware environment.
2. OpenStack environment configured and accessible.
3. [Migration Plan ](https://docs.trilio.io/openstack/t4o-5.x/user-guide/vmware-migration/migration-plans/how-to-guide-creating-a-migration-plan)created with the desired VMs selected.

### Steps to Initiate a Migration Using Horizon

1. **Log in to the OpenStack Dashboard (Horizon):**
   * Use your credentials to log in to the OpenStack Dashboard.
2. **Navigate to the VMware Migration section:**
   * In the OpenStack Dashboard, locate and click on the **VMware Migration** under the **Project** tab.
3. **Initiate Migration:**
   * If unsure whether the "**Migration Plan**" has initiated "**Discover VMs**" or not, it can be re-initiated before starting the migration.
   * Within the Migration Plan, look for the option **Migrate** to initiate migration.
   * It will pop up one wizard for collecting the user inputs.
4. **Provide Migration Details:**
   * **Migration Name**: Enter a unique and meaningful **name** for the Migration.
   * **Migration Description**: Optionally, add a detailed **description** to provide context for the migration.
   * **Migration Type**: Select the Migration Type from the drop-down. Refer to [this page](https://docs.trilio.io/openstack/t4o-5.x/deployment/software-driven-migration-vmware-to-openstack/trilios-approach#migration-types) for more information about the migration types that Trilio supports.
   * **Cutover Option:** If the selected migration type is **Warm Migration**, then the user has an option to select the Cutover option to be automatic, otherwise the cutover will be user initiated by default.
5. **Map the Networks:**
   * This section has a comprehensive list of all the unique networks found in all the VMs that are part of that Migration Plan.
   * Select the OpenStack networks, to which the VM's networks need to map.
6. **Map the Volume Types:**
   * This section has a comprehensive list of all the unique Datastores found in all the VMs that are part of that Migration Plan.
   * Select the OpenStack Volume types to which the VM's Datastores need to be mapped.
7. **Select VMs:**
   * Select the VMs of the Migration Plan that needs to be migrated to the OpenStack.
   * Verify the details of the VM to be migrated by clicking the **"+"** sign on the VMs.
8. **Start Migration:**
   * Start the migration by clicking the **Migrate** button.
   * Observe the progress and status of the migration in the OpenStack Dashboard.
     * If **Warm migration** is selected with manual cutover, then the migration will get into a **Paused** state where the user needs to resume it to continue the migration process.

### **Post-Migration Tasks**

* Verify that Instances are created with storage volumes, networking, and security groups attached.
* Verify if the Instances are booting up.
* As mentioned on the [Limitations](https://docs.trilio.io/openstack/t4o-5.x/deployment/software-driven-migration-vmware-to-openstack/limitations) page, the user may have to set up the network by accessing the console of the instance.
* Validate the connectivity of the VMs created on OpenStack.
* After migration, Trilio updates the cloud-init configuration on the migrated instance to disable most cloud-init modules. This prevents the instance from reinitializing during its first boot.

  If desired, users can revert these changes to re-enable and reinitialize cloud-init on the migrated instances.

  * **On Linux VMs**
    * A new configuration file is created at:

      ```
      /etc/cloud/cloud.cfg.d/99-migration-disable.cfg
      ```
  * **On Windows VMs**
    * The cloud-init configuration file is modified at:

      ```
      C:\Program Files\Cloudbase Solutions\Cloudbase-Init\conf\cloudbase-init.conf
      ```
    * A backup of the original configuration file is saved at:

      ```
      C:\Program Files\Cloudbase Solutions\Cloudbase-Init\conf\cloudbase-init.conf.bak
      ```

### A Note to the User

The Migration Plan will enter a "**Locked**" state while its migration is in progress. A new migration for that plan can be initiated once the running migration is available or has encountered an error and the Plan is in an "**Available**" state.

### Conclusion

Congratulations! You have successfully run a migration for VMs from VMware to OpenStack using the specified migration type. Ensure to validate the results and perform necessary tests to confirm the success of the migration process.