ONTAP 9.14

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SnapMirror Business Continuity overview

SnapMirror Business Continuity (SM-BC), also known as SnapMirror active sync, enables business services to continue operating even through a complete site failure, supporting applications to fail over transparently using a secondary copy. Neither manual intervention nor additional scripting is required to trigger a failover with SM-BC.

SM-BC is available beginning with ONTAP 9.8. SM-BC is supported on ETERNUS AX clusters or All-Flash SAN Array (ASA) clusters, where the primary and secondary clusters can be either ETERNUS AX or ASA. SM-BC protects applications with iSCSI or FCP LUNs.


SM-BC provides the following benefits:

  • Continuous availability for business-critical applications

  • Ability to host critical applications alternately from primary and secondary site

  • Simplified application management using consistency groups for dependent write-order consistency

  • The ability to test failover for each application

  • Instantaneous creation of mirror clones without impacting application availability

  • Beginning with ONTAP 9.11.1, SM-BC supports single-file SnapRestore.

  • Beginning with ONTAP 9.14.1, SM-BC supports Windows Failover Clustering and SCSI 3 persistent reservations, improving high availability.

Use cases

Application deployment for zero recovery time object (RTO)

In an SM-BC deployment, you will have a primary and secondary cluster. A LUN in the primary cluster (1LP) will have a mirror (L1s) on the secondary; both LUNs share the same serial ID and are reported as read-write LUNs to the host. Read and write operations, however, are only serviced to the primary LUN, 1LP. Any writes to the mirror L1S are served by proxy.

Disaster scenario

With SM-BC, you can synchronously replicate multiple volumes for an application between sites at geographically dispersed locations. You can automatically failover to the secondary copy in case of disruption of the primary, thus enabling business continuity for tier one applications.


The following figure illustrates the operation of the SnapMirror Business Continuity feature at a high level.

SnapMirror Business Continuity workflow

In section one of the diagram, an application is deployed on a SVM in the primary data center. The volumes that have been added to the primary consistency group are protected with SM-BC and are mirrored to secondary consistency group at a secondary data center. The volumes in the primary consistency group will failover to the mirrored consistency group in the event of a disruption. Volumes not in a mirrored consistency group are not served in the event of a failover.

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