# Open Replication for Amazon FSx for NetApp ONTAP with Cascading Support

When you use cascading with the Open Replication feature, you can replicate snapshots from a primary copy to a mirror copy or a vault copy (the secondary copy). Then, you can replicate the secondary copy to another mirror copy or vault copy (the tertiary copy).

## Cascading Configurations That You Can Use

You can use the following cascading configurations:

Cascading configuration | Source copy | Method of replication | Secondary copy | Method of replication | Tertiary copy
--- | --- | --- | --- | --- | ---
Primary-mirror-mirror (PMM) | snapshot primary copy of a source volume | mirror | mirror copy of a primary copy | mirror | mirror copy of a mirror copy
Primary-mirror-vault (PMV) | snapshot primary copy of a source volume | mirror | mirror copy of a primary copy | vault | vault copy of a mirror copy
Primary-vault-mirror (PVM) | snapshot primary copy of a source volume | vault | vault copy of a primary copy | mirror | mirror copy of a vault copy
Primary-vault-vault (PVV) | snapshot primary copy of a source volume | vault | vault copy of a primary copy | vault | vault copy of a vault copy

## Storage Virtual Machine Mappings

For the creation of the replica copy to complete successfully, you must configure storage virtual mappings (SVM) on all secondary snapshot copies. During snapshot replication, if a source volume has multiple relationships, the Commvault software uses SVM mappings to define the precedence for selecting relationships.

## Copy Precedence

When you create the first snapshot copy that is a vault copy, a replica copy, or a mirror copy, that snapshot copy is the default copy. Other snapshot copies that are associated with that storage policy are non-default copies.

## Terminology

This documentation uses the following terminology:

Term | Definition
--- | ---
default vault/replica copy | The first vault copy or replica copy that you create and associate with a storage policy whose source copy is a snap primary copy is the default vault copy or replica copy. Subsequent vault/replica copies that you create are referred to as non-default vault/replica copies. Replace "vault/replica copies" with "vault copies or replica copies".
default mirror copy | The first copy of type mirror that you create is the default mirror copy. Subsequent mirror copies that you create are referred to as non-default mirror copies.

## Related Topics

To read about the relationships that you need to create for cascading configurations, see Creating Relationships for Open Replication for Amazon FSx for NetApp ONTAP.

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