vSphere Replication can protect individual virtual machines and their virtual disks by replicating them from one vCenter Server instance to another.
When you configure replication, you set a recovery point objective (RPO) to determine the period of time between replications. For example, an RPO of 1 hour seeks to ensure that a virtual machine loses the data for no more than 1 hour during the recovery. For smaller RPO values, less data is lost in a recovery, but more network bandwidth is consumed keeping the replica up to date.
Every time that a virtual machine reaches its RPO target, vSphere Replication records approximately 3800 bytes of data in the vCenter Server events database. If you set a low RPO period, this can quickly create a large volume of data in the database. To avoid creating large volumes of data in the vCenter Server events database, limit the number of days that vCenter Server retains event data. See Configure Database Retention Policy in the vCenter Server and Host Management Guide. Alternatively, set a higher RPO value.
vSphere Replication guarantees crash consistency amongst all the disks that belong to a virtual machine. If you use VSS quiescing, you might obtain a higher level of consistency. The available quiescing types are determined by the virtual machine's operating system. See Compatibility Matrixes for vSphere Replication 5.8 for Microsoft Volume Shadow Copy Service (VSS) quiescing support for Windows virtual machines.
You can use vSphere Replication with a Virtual SAN datastore on the source and target sites. See Using vSphere Replication with Virtual SAN Storage for the limitations when using vSphere Replication with Virtual SAN.
Prerequisites
Verify that you have deployed a vSphere Replication appliance at both sites.
Procedure
Results
vSphere Replication starts an initial full synchronization of the virtual machine files to the designated datastore on the target site.