To ensure a successful vSphere Replication deployment, follow the sequence of tasks required.
vSphere Replication uses the replication technologies included in ESXi with the assistance of virtual appliances to replicate virtual machines between source and target sites.
The vSphere Replication appliance registers as an extension with the corresponding vCenter Server instance. For example, on the source site, the vSphere Replication appliance registers with the vCenter Server instance on the source site. Only one vSphere Replication appliance is allowed per vCenter Server.
The vSphere Replication appliance contains an embedded vSphere Replication server that manages the replication process. To meet the load balancing needs of your environment, you might need to deploy additional vSphere Replication servers at each site. Additional vSphere Replication servers that you deploy are themselves virtual appliances. You must register any additional vSphere Replication server with the vSphere Replication appliance on the corresponding site.
The vSphere Replication appliance automatically installs an encryption agent VIB on all ESXi hosts from the vCenter Server inventory. The encryption agent is used to encrypt the outgoing replicated data of the virtual machines that run on these ESXi hosts.
When using vSphere Replication, all hosts within the vCenter Server inventory are registered automatically. If you want to exclude hosts or hosts under a given cluster or datacenter from registration in vSphere Replication, you can tag them with the com.vmware.vr.disallowedHost tag. This is valid for the incoming replications on the target site. The tagged hosts are still used for outgoing replications and the virtual machines on the disallowed hosts can be replicated.
The vSphere Replication appliance provides a virtual appliance management interface (VRMS Appliance Management Interface). You can use the VRMS Appliance Management Interface to perform initial configuration and reconfigure the vSphere Replication database, network settings, public-key certificates, and passwords for the appliances.