Replication Components

The following infrastructure components are engaged in the replication process:

• Backup server
• Source host and target host with associated volumes
• Backup repository (only for snapshot replica)
• [Optional] Off-host backup proxy
• [Optional] WAN accelerators

Backup Server

The backup server is the configuration, administration and management core of the replication infrastructure. You can use the backup server to set up all components required for the replication process and to configure replication jobs. During the replication process, the backup server coordinates replication tasks, controls resource allocation and replica job scheduling.

Source and Target Hosts

The source host and the target host produce two terminal points between which replicated VM data is moved. The role of a target can be assigned to a single Microsoft Hyper-V host or to a Microsoft Hyper-V cluster.

If you assign a Microsoft Hyper-V cluster as a target, the replication job is performed even if one of the cluster hosts fails. At the first session of the replication job, the VM replica is registered in the cluster. At every subsequent job session, Veeam Backup & Replication detects the VM in the cluster and transports incremental data to the target. Change of the cluster owner does not affect the replication job.

Off-Host Backup Proxies

To collect, transform and transport VM data during the VM replication process, Veeam Backup & Replication uses Veeam Data Mover Services. Data Mover Services communicate with each other and maintain a stable connection.

For every replication job, Veeam Backup & Replication requires three Veeam Data Mover Services:

• Source-side Data Mover Service. The source-side Data Mover Service runs on the source host or on the off-host backup proxy, depending on the replication scenario.
• Target-side Data Mover Service. The target-side Data Mover Service runs on the target host.
• Data Mover Service hosted on the backup repository (not required for legacy replica jobs)

During replication, the source-side Data Mover Service interacts with the source host and the target-side Data Mover Service interacts with the target host. The Data Mover Service hosted on the backup repository works with replica metadata files.

Backup Repository

The backup repository stores VM replica metadata. The backup repository must be deployed in the source site, as close to the source host as possible. When you perform incremental replication, the source-side Data Mover Service communicates with the Data Mover Service on the backup repository to obtain replica metadata and quickly detect changed blocks of data between two replica states.

WAN Accelerators

WAN accelerators are optional components in the replication infrastructure. You can use WAN accelerators if you replicate VMs over a slow connection or over WAN.

In the replication process, WAN accelerators are responsible for global data caching and deduplication. To use WAN acceleration, you must deploy two WAN accelerators in the following manner:

• The source WAN accelerator must be deployed in the source side, close to the source host or off-host backup proxy running the source-side Data Mover Service.
• The target WAN accelerator must be deployed in the target side, close to the target host running the target-side Data Mover Service.