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# Create SRDF pairs

SRDF groups provide a collective data transfer path linking volumes of two separate storage systems.

## Prerequisites

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

Creation of an SRDF pair can be blocked when the R2 is larger than the R1. This feature requires that you disable the SYMAPI_RDF_CREATEPAIR_LARGER_R2 option in the SYMAPI options file (enabled by default). For more information about disabling SYMAPI options, see the Solutions Enabler Installation Guide.

The cascaded R1 -> R21 -> R2 configuration of which an SRDF pair can be part, depends on the HYPERMAX or PowerMax OS version of each of the devices. The following combinations are supported:

Unisphere supports creating SRDF pairs in a concurrent SRDF in a SRDF/Metro configuration resulting in one Metro SRDF mirror and one Async or Adaptive Copy SRDF mirror.

| NOTE: The following restrictions apply: Adding a Metro SRDF mirror when the device is part of an SRDF/Metro configuration. Adding a Metro SRDF mirror when the device is an R2 device. Adding a non-Metro SRDF R2 mirror to a device that has a Metro SRDF mirror. Adding a Metro SRDF mirror when the non-Metro SRDF mirror is in Synchronous mode. Adding a non-Metro SRDF mirror in Synchronous mode when the device is part of an SRDF/Metro configuration. Operations that make the Metro SRDF mirror RW on the SRDF link are not allowed when the SRDF/Metro device is the target of the data copy from the non-Metro SRDF mirror. Operations that make the non-Metro SRDF mirror RW on the SRDF link and result in the data copy to the Metro device are not allowed when the Metro SRDF mirror is RW on the SRDF link. The Create Pair - Invalidate R1 operation is not allowed on the non-Metro SRDF mirror when it results in a Metro device becoming write-disabled (WD). This operation is blocked on the SRDF groups that Global Mirror uses.

It is possible to create a SRDF/Metro device pair when SRDF/Metro exists in a current group or an empty SRDF group exists on the storage device.

SRDF/Metro does not support CKD devices.

Only CKD storage groups are selectable if the volumes chosen are of that emulation.

Adding to storage groups lists storage groups which are either empty or not a parent, that is, child or stand-alone storage groups which already contain devices. These groups must have those devices in the SRDF group which the wizard is being run against, and have the devices of the same SRDF polarity (R1s or R2s).

This procedure supports adding SRDF pairs to a SRDF/Metro group.

## About this task

To create an SRDF pair:

## Steps

1. Select the storage system.
2. Select Data Protection > SRDF Groups to open the SRDF Groups list view.
3. Select the SRDF group and click Create Pairs to open the Create SRDF Pairs dialog box. This selection determines the remote storage system.
4. Select Mirror Type to apply to the local devices.
5. Select SRDF Mode.
6. Select one of the following options:
   - Invalidate R1—Invalidates the source R1 devices so that a full copy can be initiated from the remote mirror.
   - Invalidate R2—Invalidates the target R2 devices so that a full copy can be initiated from the remote mirror.
   - Establish—Begins a full copy from the source to the target, synchronizing the dynamic SRDF pairs in the device file.
   - Restore—Begins a full copy from the target to the source, synchronizing the dynamic SRDF pairs in the device file.
   - Format—No data resynchronization is done between source and target dynamic SRDF pairs in the device file after all tracks are cleared on what will become the R1 and R2 side.
7. Optional: Select No WD—bypasses the check that ensures that the target of the operation is not writable by the host.
8. Click Next to go to the Local Volumes page.
9. To perform manual selection for local devices, turn Automatic Selection off.
10. Specify criteria to find the volumes of interest, and choose volumes.
11. Click Add to Storage Group checkbox and select a storage group.
12. Click Next to go to the Remote Volumes page.
13. To perform manual selection for remote devices, turn Automatic Selection off.
14. Click Add to Storage Group checkbox and select a storage group.
15. Click Next to go to the Summary page.
16. Review the changes.
17. 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.