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Replication is a software feature that synchronizes data to another system at the same site or to a different location. Replicating data helps to provide data redundancy and safeguards against failures or natural disasters at the main production site. Having a remote disaster recovery (DR) site protects against system and site-wide outages. It also provides a remote location that can resume production and minimize downtime due to a disaster. The PowerStore platform offers many data protection solutions that can meet disaster recovery needs in various environments.
Starting with PowerStoreOS 3.0, asynchronous file replication is available. Asynchronous replication can be used to protect against a storage system outage by creating a copy of data on a remote system at any distance.
The asynchronous replication for PowerStore is designed to have minimal impact on host I/O latency. Host writes are acknowledged when they are saved to the local storage resource, and no additional writes are needed for change tracking. Because write operations are not immediately replicated to a destination resource, all writes are tracked on the source. This data is replicated during the next synchronization.
With protection policies, asynchronous replication uses the concept of a recovery point objective (RPO). The RPO, measured in units of time, is the acceptable amount of data that may be lost due to an outage. This delta of time also affects the amount of data that must be replicated during the next synchronization. It also reflects the amount of potential data loss in a disaster scenario.
Starting with PowerStoreOS 4.0, asynchronous replication metrics can be viewed on the source system through PowerStore Manager, PSTCLI, or REST API. As shown in Figure 41, the following metrics are available at the file system and NAS server levels:
For more information about file asynchronous replication, see the Dell PowerStore: Replication Technologies white paper.
Starting with PowerStoreOS 4.0, synchronous file replication is available. Synchronous replication is a zero RPO solution. This ensures both sites always have consistent copies of the data, eliminating the possibility of data loss.
When using synchronous replication, the write operation behavior changes since it must be committed to both systems in real-time.
This ensures that both sites always have an identical copy of the data. Since the final host acknowledgement cannot be completed until both systems provide acknowledgement, the latency between the two sites is crucial. It is highly recommended to ensure the sites are within 100 kilometers or 60 miles of each other and has a Round-Trip Time (RTT) of 5ms or less.
Synchronous replication includes performance metrics that show the session bandwidth. This provides information on how much bandwidth is being used to copy data across the link between the two systems.
For more information about file synchronous replication, see the Dell PowerStore: Replication Technologies white paper.