Administrator Guide

Requirement Description
QoS Definition A quality of service (QoS) definition must be set up for the replication on the source
Storage Center.
Related concepts
Connecting to Remote Storage Centers
Related tasks
Add a Storage Center
Creating and Managing Replication QoS Definitions
Replication Behavior When a Destination Volume Fails
When the destination volume becomes unavailable, each replication type behaves slightly differently. The replication types also recover
differently when the destination volume comes back online.
Scenario Asynchronous Replication Synchronous Replication
Destination volume is unavailable Allows IO requests to the source
volume
• High Consistency mode: Fails IO requests to the source
volume
• High Availability mode: Allows IO requests to the source
volume
Destination volume comes back
online
Resumes transferring snapshots
from the source volume and re-
copies Active Snapshot data (if
enabled)
• High Consistency mode: Resumes accepting IO requests to
the source volume
• High Availability mode: Resumes transferring snapshots from
the source volume and copies the Active Snapshot data that
was missed while the destination volume was unavailable
Replicating a Single Volume to Multiple Destinations
Multiple replications can be configured for a single source volume. Two topologies are supported:
• Mixed mode: A source volume is replicated in parallel to multiple Storage Centers.
Example: Two replications are created in parallel:
• Replication 1: Storage Center A → Storage Center B
• Replication 2: Storage Center A → Storage Center C
• Cascade mode: A source volume is replicated in series to multiple Storage Centers.
Example: Two replications are created in series:
• Replication 1: Storage Center A → Storage Center B
• Replication 2: Storage Center B → Storage Center C
Topology Limitations for Volumes Associated with Multiple
Replications
The following limitations apply to volumes that are associated with multiple replications.
• Only one synchronous replication can be configured per source volume. Subsequent replications must be asynchronous.
• For cascade mode (replications configured in series), only the first replication can be a synchronous replication. Subsequent
replications in the series must be asynchronous.
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Storage Center Replications and Live Volumes