Choosing a replication policy

A replication policy defines how the storage system replicates data from a source volume to a destination volume. You must choose a replication policy when you set up data replication in Cloud Manager.

What replication policies do

The ONTAP operating system automatically creates backups called Snapshot copies. A Snapshot copy is a read-only image of a volume that captures the state of the file system at a point in time.

When you replicate data between systems, you replicate Snapshot copies from a source volume to a destination volume. A replication policy specifies which Snapshot copies to replicate from the source volume to the destination volume.
Note: Replication policies are also referred to as protection policies because they are part of SnapMirror and SnapVault technologies that provide disaster recovery protection and disk-to-disk backup and recovery.

The following image shows the relationship between Snapshot copies and replication policies:

This illustration shows Snapshot copies on a source volume and a replication policy that specifies replication of all or specific Snapshot copies from the source volume to the destination volume.

Types of replication policies

There are three types of replication policies:
  • A SnapMirror policy replicates newly created Snapshot copies to a destination volume.

    You can use these Snapshot copies to protect the source volume in preparation for disaster recovery or for one-time data replication. You can activate the destination volume for data access at any time.

  • A SnapVault policy replicates specific Snapshot copies to a destination volume and typically retains them for a longer period of time than you would on the source volume.

    You can restore data from these Snapshot copies when data is corrupted or lost, and retain them for standards compliance and other governance-related purposes.

    How SnapVault policies work

  • A SnapMirror and SnapVault policy provides both disaster recovery and long-term retention.

Each system includes default SnapMirror and SnapVault policies, which work well for many situations. If you find that you need custom policies, you can create your own using System Manager.

The following images show the difference between SnapMirror and SnapVault. A SnapMirror policy mirrors the Snapshot copies available on the source volume.

This illustration shows Snapshot copies on a source volume and a SnapMirror destination volume that mirrors the source volume.

A SnapVault policy typically retains Snapshot copies longer than they are retained on the source volume:

This illustration shows Snapshot copies on a source volume and a SnapVault destination volume that includes more Snapshot copies because SnapVault retains Snapshot copies for long-term retention.