Veeam Backup & Replication uses the following components for the replication process:
- Backup server
- Source host and target host with associated volumes
- [Optional] Off-host backup proxy
- Backup repository (only for snapshot replica)
- [Optional] WAN accelerators
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.
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 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. During the first session of the replication job, the VM replica is registered in the cluster. During 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.
To collect, transform and transport VM data during the VM replication process, Veeam Backup & Replication uses Veeam Data Movers. Data Mover Services communicate with each other and maintain a stable connection.
For every replication job, Veeam Backup & Replication requires 3 Veeam Data Movers:
- Source Veeam Data Mover runs on the source host or off-host backup proxy, depending on the replication scenario.
- Target Veeam Data Mover runs on the target host.
- Veeam Data Mover hosted on the backup repository (not required for legacy replica jobs)
During replication, the source Veeam Data Mover interacts with the source host, and the target Veeam Data Mover interacts with the target host. The Veeam Data Mover hosted on the backup repository works with replica metadata files.
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 Veeam Data Mover communicates with the Veeam Data Mover on the backup repository to obtain replica metadata and quickly detect changed blocks of data between two replica states.
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 Veeam Data Mover.
- The target WAN accelerator must be deployed in the target side, close to the target host running the target Veeam Data Mover.
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