VMware vSphere Replication is a hypervisor-based, asynchronous replication solution that is fully integrated with VMware vCenter Server. It uses a proprietary replication engine developed by VMware and is included with VMware vSphere Essentials Plus Kit and higher editions of VMware vSphere. While VR works well with vSAN storage in a VxRail hyperconverged environment, it is completely independent of the underlying storage and allows for replication between heterogeneous storage types. This is useful when a VxRail system is part of a larger virtualization environment that includes SAN or other storage types. VR provides data protection locally within the same vCenter environment as well as disaster recovery and avoidance to another vCenter site. It also supports replication to Service Provider clouds such as vCloud Air.
The figure below shows VR replication between two VxRail sites.
Figure 61. VMware vSphere Replication with VxRail
In this example, several VMs are replicated to a remote site with a RPO of 15 minutes. The remote site maintains multiple VM images, allowing roll back to different points-in-time.
The VR components that transmit replicated data are built into vSphere and use Secure Sockets Layer (SSL) connection. A best practice is to isolate network traffic to improve performance and security. VR also includes one or more prebuilt Linux-based vSphere Replication vApps. The first virtual appliance is referred to as the vSphere Replication Management server. It receives replicated data, manages authentication, and maintains mappings between the source virtual machines and the replicas at the target location. Each appliance requires 18GB of VMDK storage, 4GB of memory, and either two or four virtual CPUs.
VR configuration includes specifying the Recovery Point Objectives (RPO) within a range of 15 minutes to 24 hours as well as the number of point-in-time time images to maintain. This is all done from within the vSphere web client using a simple wizard. Once replication has been configured for a virtual machine, vSphere Replication begins the initial full synchronization of the source virtual machine to the target location. The time required to complete this initial synchronization can vary depending on the amount of data that must be replicated and the amount of available network bandwidth. After the initial full synchronization, only changed data is transmitted in each replication cycle, minimizing the network bandwidth requirements.
The replicated data is first written to a redo log. After all changes for the current replication cycle have been received and written to the redo log, the data in the redo log is merged into the base image. This process ensures a consistent and recoverable VM image is available at all times.
vSphere Replication delivers flexible, reliable and cost-efficient replication for data protection and disaster recovery. It is seamlessly integrated within the VMware product stack for simple deployment, configuration, and management.