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Consistency groups aggregate volumes to enable the management and configuration of a common set of properties to a group of volumes in a metro node Local or metro node Metro configuration, but not both concurrently. Synchronous consistency groups provide a way to apply rule sets and other properties to a group of volumes in either configuration. Some configurable properties of consistency groups include:
Write-through caching is used on the members of the consistency group to ensure write order fidelity is guaranteed by completing all writes to disk before acknowledging the write to the host.
Note: For Oracle environments, create a single metro node consistency group for each Oracle database or for ASM disks from related ASM disk groups hosting a single database or multiple databases. Include in that consistency group all the virtual volumes that make up the database. In some scenarios, this can be a requirement rather than a recommendation. For example, if AppSync is used to protect an Oracle, AppSync may require all virtual volumes reside in only one metro node consistency group.
Consistency groups in metro node do not control and are not used for snapshots in PowerStore. Therefore, if PowerStore snapshots are to be used with metro node, the volumes containing the Oracle database must exist in one or more PowerStore write-consistent volume group. The number of PowerStore write-consistent volume groups needed, is dictated by application and infrastructure needs. For more information about metro node consistency groups, PowerStore volume groups, and AppSync, see References.
Specific information about how to create a metro node consistency group for a Local and Metro configuration is covered in the Configuring and provisioning metro Local storage and Configuring and provisioning metro node Metro storage sections below.