The backup infrastructure in a Hyper-V environment comprises the following components:
|•||One or more source hosts with associated volumes|
|•||Off-host backup proxy server (optional)|
|•||One or more backup repositories|
The source host and the repository produce two terminal points between which VM data is moved. Backup data is collected, transformed and transferred with the help of Veeam transport services. Veeam Backup & Replication uses a two-service architecture — one Veeam transport service interacts with the source host, and the other one interacts with the repository. The Veeam transport services communicate with each other and maintain a stable connection. All backup infrastructure components engaged in the job make up a data pipe. VM data is moved over this data pipe block by block, so that processing of a single VM includes multiple processing cycles.
When a new backup session is started, the target-side Veeam transport service obtains the job instructions and communicates with the source-side Veeam transport service to begin data collection.
|1.||After a VSS snapshot is created, the source-side Veeam transport service copies VM data from the volume shadow copy. While copying, the source-side Veeam transport service performs additional processing — it consolidates the content of virtual disks by filtering out overlapping snapshot blocks, zero-data blocks and blocks of swap files. During incremental job runs, the Veeam transport service retrieves only those data blocks that have changed since the previous job run (note that with changed block tracking enabled, the speed of incremental backup dramatically increases). Copied blocks of data are compressed and moved from the source-side Veeam transport service to the target-side transport service.|
|2.||The target-side Veeam transport service deduplicates similar blocks of data and writes the result to the backup file in the backup repository.|
Veeam Backup & Replication supports a number of backup scenarios that depend on the type of repository you use and its location. For details, see Backup Repository.