SnapMirror active sync utilizes peered clusters to ensure your data is available in the event of a failover scenario. The ONTAP Mediator is a key resource ensuring business continuity, monitoring the health of each cluster. To configure SnapMirror active sync, you must first install the ONTAP Mediator and ensure you primary and secondary clusters are configured properly.

Once you have installed the ONTAP Mediator and configured your clusters, you must Initialize the ONTAP mediator for SnapMirror active sync the ONTAP Mediator for use with SnapMirror active sync. You must then create, initialize, and map the consistency group for SnapMirror active sync.

ONTAP Mediator

The ONTAP Mediator establishes a quorum for the ONTAP clusters in an SnapMirror active sync relationship. It coordinates automated failover when a failure is detected, determining which cluster acts as the primary and ensuring data is served to and from the correct destination.

Prerequisites for the ONTAP Mediator

The ONTAP Mediator includes its own set of prerequisites. You must meet these prerequisites before installing the mediator.

For more information, see Prepare to install the ONTAP Mediator service.
By default, the ONTAP Mediator provides service through TCP port 31784. You should make sure that port 31784 is open and available between the ONTAP clusters and the mediator.

Install the ONTAP Mediator and confirm cluster configuration

Proceed through each of the following steps. For each step, you should confirm that the specific configuration has been performed. Use the link included after each step to get more information as needed.

Steps

Install the ONTAP Mediator service before you ensure that your source and destination clusters are configured properly.

Prepare to install or upgrade the ONTAP Mediator service
Confirm that a cluster peering relationship exists between the clusters.

The default IPspace is required by SnapMirror active sync for cluster peer relationships. A custom IPspace is not supported.

Configure peer relationships
Confirm that the Storage VMs are created on each cluster.

Creating an SVM
Confirm that a peer relationship exists between the Storage VMs on each cluster.

Creating an SVM peering relationship
Confirm that the volumes exist for your LUNs.

Creating a volume
Confirm that at least one SAN LIF is created on each node in the cluster.

Considerations for LIFs in a cluster SAN environment
Confirm that the necessary LUNs are created and mapped to an igroup, which is used to map LUNs to the initiator on the application host.

Create LUNs and map igroups
Rescan the application host to discover any new LUNs.

Initialize the ONTAP mediator for SnapMirror active sync

Once you have installed the ONTAP Mediator and confirmed you cluster configuration, you must initialize the ONTAP Mediator for cluster monitoring. You can initialize the ONTAP Mediator using ONTAP System Manager or the ONTAP CLI.

ONTAP System Manager

With ONTAP System Manager, you can configure the ONTAP Mediator server for automated failover. You can also replace the self-signed SSL and CA with the third party validated SSL Certificate and CA if you have not already done so.

From ONTAP 9.8 through 9.14.1, SnapMirror active sync is referred to as SnapMirror Business Continuity (SM-BC).

Steps

Navigate to Protection > Overview > Mediator > Configure.
Select Add, and enter the following ONTAP Mediator server information:
- IPv4 address
- Username
- Password
- Certificate

CLI

You can initialize the ONTAP Mediator from either the primary or secondary cluster using the ONTAP CLI. When you issue the mediator add command on one cluster, the ONTAP Mediator is automatically added on the other cluster.

Steps

Initialize Mediator on one of the clusters:

snapmirror mediator add -mediator-address IP_Address -peer-cluster cluster_name -username user_name

Example

cluster1::> snapmirror mediator add -mediator-address 192.168.10.1 -peer-cluster cluster2 -username mediatoradmin
Notice: Enter the mediator password.

Enter the password: ******
Enter the password again: ******

Check the status of the Mediator configuration:

snapmirror mediator show
```
Mediator Address Peer Cluster     Connection Status Quorum Status
---------------- ---------------- ----------------- -------------
192.168.10.1     cluster-2        connected         true
```
Quorum Status indicates whether the SnapMirror consistency group relationships are synchronized with the mediator; a status of true indicates successful synchronization.