Dell PowerStore Protecting Your Data

Synchronous replication is a replication mode in which updates to data on the source system are replicated to the destination system immediately when the update occurs (zero RPO replication). Using synchronous replication ensures that both systems are fully synchronized at any point in time. Synchronous replication guarantees zero data loss, but can cause latency, depending on the distance between the source and destination systems.

PowerStore supports synchronous remote replication for volumes, volume groups, thin clones, block snapshots, and NAS servers.

To apply synchronous replication to a storage resource, assign the resource with a protection policy that includes a synchronous replication rule. Assigning a protection policy creates a replication session which is added to the replication sessions list (Protection > Replication), and the Replication Type column displays Synchronous.

When a replication session is created, the storage resource is replicated to the destination system. When updates are made to the resource, only these updates are replicated to the destination system.

You can failover a synchronous replication session using planned or unplanned failover. For details, see the Failover section.

Unassigning the protection policy from the storage resource deletes the replication session. When the replication session is operating normally, unassigning the policy can be done only on the source system.

When you assign a protection policy that includes a synchronous replication rule, the source system has a read/write policy, while the destination system has a read-only copy of the policy. Only the read/write policy can be modified or removed. If the system that has the read/write policy is down, performing a failover switches the roles of the systems and allows you to manage the read/write protection policy from the destination system.

To enable synchronous replication, the system pair must be configured with low network latency (under five milliseconds). The configured network latency cannot be changed while synchronous replication sessions are configured for these systems.

For a summary of synchronous replication attributes and comparison to asynchronous replication and metro, see Replication Summary.