This is an archive version of the document. To get the most up-to-date information, see the current version.About Replication
Veeam Backup & Replication is built for virtual environments. It operates at the virtualization layer and uses an image-based approach for VM replication.
Veeam Backup & Replication does not install agent software inside the VM guest OS to retrieve VM data. To replicate VMs, it leverages VMware vSphere snapshot capabilities. When you replicate a VM, Veeam Backup & Replication requests VMware vSphere to create a VM snapshot. The VM snapshot can be thought of as a cohesive point-in-time copy of a VM including its configuration, OS, applications, associated data, system state and so on. Veeam Backup & Replication uses this point-in-time copy as a source of data for replication.
In many respects, replication works similarly to forward incremental backup. During the first replication cycle, Veeam Backup & Replication copies data of the original VM running on the source host, and creates its full replica on the target host. Unlike backup files, replica virtual disks are stored uncompressed in their native format. All subsequent replication cycles are incremental. Veeam Backup & Replication copies only those data blocks that have changed since the last replication job session. To keep track of changed data blocks, Veeam Backup & Replication uses different approaches. For more information, see Changed Block Tracking
Veeam Backup & Replication lets you perform onsite replication for high availability (HA) scenarios and remote (offsite) replication for disaster recovery (DR) scenarios. To facilitate replication over the WAN or slow connections, Veeam Backup & Replication optimizes traffic transmission. It filters out unnecessary data blocks such as duplicate data blocks, zero data blocks, blocks of swap files and blocks of excluded VM guest OS files, and compresses replica traffic. Veeam Backup & Replication also allows you to use WAN accelerators and apply network throttling rules to prevent replication jobs from consuming the entire network bandwidth.
In Veeam Backup & Replication, replication is a job-driven process. To perform replication, you need to configure replication jobs. A replication job is a configuration unit of the replication activity. The replication job defines when, what, how and where to replicate. One replication job can be used to process one or several VMs. You can instruct Veeam Backup & Replication to run jobs automatically by schedule or start them manually.
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