Requirements and considerations for using cross-zone replication

This article describes requirements and considerations about using the volume cross-zone replication functionality of Azure NetApp Files.

Requirements and considerations

• The cross-zone replication feature uses the availability zone volume placement feature of Azure NetApp Files.
• To establish cross-zone replication, you must create the source volume in an availability zone.
• You can’t use cross-zone replication and cross-region replication together on the same source volume.
• You can use cross-zone replication with SMB and NFS volumes. Replication of SMB volumes requires an Active Directory connection in the source and destination NetApp accounts. The destination AD connection must have access to the DNS servers or AD DS Domain Controllers that are reachable from the delegated subnet in the destination zone. For more information, see Requirements for Active Directory connections.
• The destination account must be in a different zone from the source volume zone. You can also select an existing NetApp account in a different zone.
• The replication destination volume is read-only until you fail over to the destination zone to enable the destination volume for read and write. For more information about the failover process, see fail over to the destination volume.

  Important

  Failover is a manual process. When you need to activate the destination volume (for example, when you want to fail over to the destination region), you need to break replication peering then mount the destination volume. For more information, see fail over to the destination volume

• Azure NetApp Files replication doesn't currently support multiple subscriptions; all replications must be performed under a single subscription.
• See resource limits for the maximum number of cross-zone destination volumes. You can open a support ticket to request a limit increase in the default quota of replication destination volumes (per subscription in a region).
• There can be a delay up to five minutes for the interface to reflect a newly added snapshot on the source volume.
• Cross-zone replication does not support cascading and fan in/out topologies.
• After you set up cross-zone replication, the replication process creates SnapMirror snapshots to provide references between the source volume and the destination volume. SnapMirror snapshots are cycled automatically when a new one is created for every incremental transfer. You cannot delete SnapMirror snapshots until you delete the replication relationship and volume.
• You cannot mount a dual-protocol volume until you authorize replication from the source volume and the initial transfer happens.
• You can delete manual snapshots on the source volume of a replication relationship when the replication relationship is active or broken, and also after you've deleted replication relationship. You cannot delete manual snapshots for the destination volume until you break the replication relationship.
• When reverting a source volume with an active volume replication relationship, only snapshots that are more recent than the SnapMirror snapshot can be used in the revert operation. For more information, see Revert a volume using snapshot revert with Azure NetApp Files.
• Data replication volumes support customer-managed keys.
• Large volumes are supported with cross-zone replication only with an hourly or daily replication schedule.

Large volumes configuration

Large volumes are supported in cross-zone replication. You must first register for the large volumes feature then register to use large volumes with cross-zone replication:

1. Register the feature by running the following commands:

   Register-AzProviderFeature -ProviderNamespace Microsoft.NetApp -FeatureName ANFLargeVolumesCRR
   

2. Check the status of the feature registration:

   Note

   The RegistrationState may be in the Registering state for up to 60 minutes before changing to Registered. Wait until the status is Registered before continuing.

   Get-AzProviderFeature -ProviderNamespace Microsoft.NetApp -FeatureName ANFLargeVolumesCRR
   

You can also use Azure CLI commands az feature register and az feature show to register the feature and display the registration status.

Next steps

• Understand cross-zone replication
• Create cross-zone replication relationships