IBM System Storage DS3000 Programming Manual page 475

Before you can delete an Enhanced Global Mirror Group you must remove the primary logical drive, the
secondary logical drive, and the repository logical drive from the Enhanced Global Mirror Group. The
Enhanced Global Mirror Group must be completely empty before you can delete it. You can remove these
logical drives using this command:
remove logicalDrive=["logicalDrivename"] enhancedGlobalMirrorGroup="enhancedGlobalMirrorGroupName"
Removing these logical drives from the Enhanced Global Mirror Group does not delete the logical drives.
The data is not lost.
Deleting the Enhanced Global Mirror Group first removes the remote Enhanced Global Mirror Group
then removes the local Enhanced Global Mirror Group. You can run the delete
enhancedGlobalMirrorGroup command from either the primary or secondary Enhanced Global Mirror
Group.
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Chapter 7. About Enhanced Global Mirroring premium feature