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# Create a migration session

Non-Disruptive Migration (NDM) provides a method for migrating data from a source storage system to a target storage system without application host downtime. Minimally disruptive migration enables migrations on the same supported platforms as NDM it but requires a short application outage.

## Prerequisites

See Roles and associated permissions to determine the user roles that can perform this task.

The data migration environment exists between two candidate storage systems.

The selected storage group is a masked candidate storage group.

The selected storage group does not contain only gatekeepers.

The local storage system must have online SRDF ports.

You can create a port group or alternatively, you can select an existing port group on the target storage system to use as part of the migrated Masking View.

## About this task

The precopy option allows storage to be provisioned on the target storage system without making the host of the devices visible. This option allows the application to continue running on the source storage system while data is being copied to the target.

Minimally disruptive migration allows migrations on the same supported platforms as NDM but it requires a short application outage.

See Understanding migration for additional information.

To create a migration session:

## Steps

1. Select a storage system.
2. Select STORAGE > Storage Groups.
3. Select a storage group.
4. Click and click Migrate.
5. Select the target storage system.
   Selecting Any System allows you to select from a list of target arrays sorted by performance impact (see The multi-array Migration wizard).
6. Select the target Storage Resource Pool (SRP).
   The default SRP is selected on the SRP combo if it can be calculated. Not specifying an SRP is allowed for data migration creation.
7. Optional: Clear the Enable Data Reduction check box to turn off data reduction.
   Data reduction is only allowed on All Flash systems running the HYPERMAX OS 5977 Q3 2016 Service Release or higher.
8. Optional: Click Precopy.
9. Optional (use for Minimally Disruptive Migration): Click Offline and if Offline is selected, optionally click Move Identity. Selecting Offline requires a host reboot.
10. Click NEXT.
    The Target Masking Options page is displayed. Information on one or more masking views along with their associated ports groups, ports, host, and initiators, is displayed. If WLP is enabled (statistics are available for source storage group and target storage system), a suitability score is also displayed.
11. Review the target masking options and any associated warnings (see Non-Disruptive Migration (NDM) warning messages and failure cases).
12. Optional: Click next to the port group to display a dialog allowing you to modify the port group parameters. Click OK when complete.
    is displayed for the following scenarios:
    - Single masking view
    - Multiple masking views where all masking views share the same port group.
    - Device overlap where all masking views for all SGs share the same port group and no duplicate paths are created (a duplicate path is the same initiator to port mapping in multiple masking views). When devices overlap multiple SGs with different port groups, the wizard allows you to open the edit dialog. The port group names cannot be changed, different ports can be chosen.
    - "Zoning required" cases where the port group does not exist on the target storage system:
      - If WLP is enabled, ports are pre-selected based on utilization.
      - If WLP is not enabled, you can select the ports.

    FA (Fibre Channel): Relies heavily on SE port selection rules. If source PG name exists on target storage system, use it. If no PG name match exists, but login history table entries (active and historical) exist to host initiator WWNs, put all ports in one PG and use those ports. If no zoning exists, WLP selects ports. Suitability is done using active paths for cases 1 and 2. Load is spread across all selected ports in case 3.

    FN (Fibre Channel) and SE (GigE) : Not supported.

13. Optional: Review the updated target masking options and any associated warnings.
14. Click NEXT.
15. On the Summary page, review the details. Optionally click Save Migration Report to save the migration report to a PDF file. This option is only available in cases where zoning is required.
    If zoning is required, save the zoning report and press Add to Job List . The Add to Job List is the only option available in this scenario, Run Now is not available.

    The purpose of the Zoning Report is to present the remaining zoning that is required to satisfy the NDM zoning requirements. If an initiator in an initiator group has no login history table (LHT) entries to any ports in the port group in a masking view on the target storage system, a zoning report can be generated laying out the requirements to get the migration to succeed. However, if an initiator in an initiator group has logins to some ports in a port group on the target storage system, but not all, no zoning report is offered, because the requirements of the migration have been satisfied.

16. Do one of the following:
    - Click Run Now to perform the operation now.
    - Expand Run Now and click Add to Job List to add this task to the job list, from which you can schedule or run the task at your convenience. For more information, see Schedule jobs and Preview jobs.

## Results

If the host can scan new paths on its own, it moves to Synchronized. If user rescan is needed, it stays in the Migrating state at 100% done.

If using Precopy, the result will be the Precopy state, and the next step would be to run Ready Target.

If using Offline, the migration state moves to go to CutoverSync