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# Protect storage groups using SRDF/Metro

Storage groups are a collection of devices that are stored on the array, and an application, a server, or a collection of servers use them.

## About this task

This procedure explains how to protect storage groups using SRDF/Metro, thus improving support for host applications in high availability environments.

Before you begin:

- Connectivity to remote storage system must be available.
- All storage systems that involved must be discoverable and manageable from the console.
- SRDF/Metro does not support CKD devices.

You are not allowed to set SRDF devices in the non-Metro SRDF mirror to operate in Synchronous mode.

For systems running PowerMaxOS 5978 or later, the create pair operation is blocked when the device ID types of each individual SRDF device pair are not the same (both Compatibility ID or both Mobility ID) on both sides. Device type ID conversion from a Compatibility ID to a Mobility ID is not allowed on a device once it is part of an SRDF/Metro session. Candidate IDs are restricted to those running PowerMaxOS 5978 or later when the source storage group has devices with Mobility ID in them.

Protecting a storage group using SRDF/Metro from the protection wizard is allowed when one or more of the devices in the storage group have the GCM flag set.

To protect storage groups using SRDF Metro:

## Steps

1. Select the storage system.
2. Select STORAGE > Storage Groups and select a storage group.
3. Select the storage group and click Protect.
   The Select Protection Type page displays.
4. Select High Availability using SRDF/Metro.
5. Click NEXT.
6. Select the Remote Array ID. To update the list of remote arrays, click Scan.
7. Optional: To stop the initiation of pair mirroring, clear the Establish Pairs option.
8. If Establish Pairs is checked, choose Protected by Witness or Bias.

   If Witness is unavailable on the local or remote array, the option is disabled and Bias is selected by default. If available, Witness is selected by default.

   For storage systems running HYPERMAX OS 5977 Q3 2016 or later, when the Witness radio button is selected, the Witness Candidate (Remote Array) field displays a list of physical and Virtual witnesses instances which are enabled. Disabled virtual witness instances are not displayed.

9. Optional: Change the Remote Storage Group Name, and optionally select a Remote Service Level.
   Changing the name also changes the target volume storage group name.
10. Optional: To disable data reduction, clear the Enable Data Reduction option.
11. Click NEXT.
12. Verify your selections. To change any of them, click BACK.
    Some changes may require you to make extra changes to your configuration.
13. 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.