When Veeam Backup & Replication is initially installed, the Veeam backup server coordinates all job activities and handles data traffic itself. That is, when you run a backup, replication, VM copy, VM migration job or perform restore operations, VM data is moved from source to target through the Veeam backup server. This scenario is acceptable for virtual environments where few backup jobs are performed; in large-scale environments, however, the workload on the Veeam backup server will be significant.
To take the workload off the Veeam backup server, Veeam Backup & Replication uses backup proxies. A backup proxy is an architecture component that sits between data source and target and is used to process jobs and deliver backup traffic. In particular, the backup proxy tasks include retrieving VM data from the production storage, compressing and sending it to the backup repository (for example, if you run a backup job) or another backup proxy (for example, if you run a replication job). As the data handling task is assigned to the backup proxy, the Veeam backup server becomes the “point of control” for dispatching jobs to proxy servers.
The role of a backup proxy can be assigned to a dedicated Windows server (physical or virtual) in your virtual environment. You can deploy backup proxies both in the primary site and in remote sites. To optimize performance of several concurrent jobs, you can use a number of backup proxies. In this case, Veeam Backup & Replication will distribute the backup workload between available backup proxies.
Use of backup proxies lets you easily scale your backup infrastructure up and down based on your demands. Backup proxies run light-weight services that take a few seconds to deploy. Deployment is fully automated — Veeam Backup & Replication installs the necessary components on a Windows-based server when you add it to the product console. As soon as you assign the role of a backup proxy to the added server, Veeam Backup & Replication starts the required services on it.
The primary role of the backup proxy is to provide an optimal route for backup traffic and enable efficient data transfer. Therefore, when deploying a backup proxy, you need to analyze the connection between the backup proxy and storage with which it is working. Depending on the type of connection, the backup proxy can be configured in one of the following ways (starting from the most efficient):
▪A machine used as a backup proxy should have direct access to the storage on which VMs reside or the storage where VM data is written. This way, the backup proxy will retrieve data directly from the datastore, bypassing LAN.
▪The backup proxy can be a VM with HotAdd access to VM disks on the datastore. This type of proxy also enables LAN-free data transfer.
▪If neither of the above scenarios is possible, you can assign the role of the backup proxy to a machine on the network closer to the source or the target storage with which the proxy will be working. In this case, VM data will be transported over LAN using NBD protocol.
Depending on the type of backup proxy and your backup architecture, the backup proxy can use one of the following data transport modes: Direct SAN Access, Virtual Appliance or Network. If the VM disks are located on the SAN storage and the SAN storage is added to the Veeam Backup & Replication console, the backup proxy can also use the Backup from Storage Snapshots mode. You can explicitly select the transport mode or let Veeam Backup & Replication replication automatically choose the mode. For details, see Transport Modes and Backup from Storage Snapshots.
The backup proxy uses the following services and components:
▪Veeam Installer Service is an auxiliary service that is installed and started on any Windows server once it is added to the list of managed servers in the Veeam Backup & Replication console. This service analyses the system, installs and upgrades necessary components and services depending on the role selected for the server.
▪Veeam Transport is responsible for deploying and coordinating executable modules that act as "data movers" and perform main job activities on behalf of Veeam Backup & Replication, such as communicating with VMware Tools, copying VM files, performing data deduplication and compression and so on.