vSphere Replication is a proprietary, host-based replication engine for VMware virtual machines. After initial replication of a virtual machine has been completed, changed blocks are tracked and only these deltas are sent to the target location. This approach lowers bandwidth utilization and enables more-aggressive recovery point objectives (RPOs) than manual, full-system virtual machine copies.
What are use cases for VMware vSphere Replication?

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Replicate one or more virtual machines:
- Within a VMware vSphere cluster or across vSphere clusters at the same site for local data protection, virtual machine migration, and disaster recovery
- Across vSphere clusters at different sites for cross-site data protection, virtual machine migration, and disaster recovery
- From an on-premises data center to a VMware vCloud Air Disaster Recovery service provider for disaster recovery
- From one on-premises data center to another for use with VMware vCenter Site Recovery Manager (SRM)
What are the minimum requirements for enabling VMware vSphere Replication?
Using vSphere Replication as a standalone solution without VMware vCenter Site Recovery Manager requires VMware vCenter Server 5.1 or higher and VMware vSphere 5.1 or higher.
Use of vSphere Replication with vCenter Server 5.0 and vSphere 5.0 requires vCenter Site Recovery Manager 5.0. The vSphere edition must be VMware vSphere Essentials Plus Kit or higher. Virtual machines must be configured with virtual machine hardware version 7 or higher. The Guest OS Quiescing feature of vSphere Replication requires VMware Tools.
What terms are commonly used with VMware vSphere Replication?
vSphere Replication: Name of the VMware vSphere feature that enables host-based replication.
vSphere Replication Management Server: Virtual appliance containing both the management component for vSphere Replication and the component that receives replicated data (vSphere Replication Server).
vSphere Replication Server: Virtual appliance containing the component that receives replicated data but does not contain the management component.
vSphere Replication Agent: Component built into vSphere that tracks the changes in a replicated virtual machine and transmits these changes to a vSphere Replication Management Server or vSphere Replication Server virtual appliance.
Recovery point objective (RPO): Policy that defines the maximum tolerable amount of data loss, measured as a period of time—typically, minutes or hours. For example, a 60-minute RPO means that except for any changes that occurred to the source in the preceding 60 minutes, the replicated copy, or “target,” should contain the same data as the source.