Administrator Guide

Synchronous replication features
15 Dell EMC SC Series: Synchronous Replication and Live Volume | CML1064
exposure as well as the replication link bandwidth consumed to recover. Minimal recopy is also employed in
high consistency mode should the destination volume become unavailable during initial synchronization or an
administrator invoked a pause operation on the replication.
Flushing journaled writes to the destination volume to regain volume consistency
3.3 Asynchronous replication capabilities
Synchronous replication has seen numerous improvements over time and includes key features that were
previously associated only with asynchronous replication.
3.3.1 Snapshots and consistency groups
The most notable asynchronous feature is the replication of SC Series snapshots. In the past, only the active
snapshot data was replicated from source to destination. With snapshots automatically replicated to the
destination site, customers have more flexibility in recovery options with many historical restore points to
choose from. By virtue of having snapshot functionality, synchronous replication can be integrated with
consistency groups and Replay-Manager-created snapshots across volumes to enable snapshot interval
consistency across replicated volumes. In high consistency mode, snapshot consistency will be guaranteed.
In high availability mode, snapshot consistency is highly likely.
Note: Consistent snapshots may be created for asynchronous and synchronous replications. However,
consistent snapshots are not supported with Live Volumes.
3.3.2 Pause
Synchronous replications configured in either high consistency or high availability modes can be paused
without impacting availability of applications relying on the replication source volume. Pausing replication can
facilitate multiple purposes. For example, it can be used to relieve replication link bandwidth utilization. In
designs where replication bandwidth is shared, other processes can temporarily be given burstable priority.
Pausing may also be preferred in anticipation of a scheduled replication link or fabric outage.