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Backup

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Unlike traditional backup tools designed to work with physical machines, Veeam Backup & Replication is built specifically for virtual environments. It operates at the virtualization layer and uses an image-based approach for VM backup. To retrieve VM data, no agent software needs to be installed inside the guest OS. Instead, Veeam Backup & Replication leverages VSS snapshot capabilities. When a new backup session starts, a VSS snapshot is taken to create 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 to retrieve VM data. Image-based backups can be used for different types of recovery, including Instant VM Recovery, full VM recovery, VM file recovery and file-level recovery.

Use of the image-based approach allows Veeam Backup & Replication to overcome shortfalls and limitations of traditional backup (such as, the necessity to provide guest OS credentials for every VM, significant resource overhead on the VM and hypervisor during the backup process, management overhead and so on). It also helps streamline the restore process — to recover a single VM, there is no need to perform multiple restore operations. Veeam Backup & Replication uses a cohesive VM image from the backup to restore a VM to the required state without the necessity for manual reconfiguration and adjustment.

In Veeam Backup & Replication, backup is a job-driven process where one backup job can be used to process one or more VMs. A job is a configuration unit of the backup activity. Essentially, the job defines when, what, how and where to back up. It indicates what VMs should be processed, what components should be used for retrieving and processing VM data, what backup options should be enabled and where to save the resulting backup file. Jobs can be started manually by the user or scheduled to run automatically.

The resulting backup file stores compressed and deduplicated VM data. All backup files created by the job are located in a dedicated job folder on a backup repository. Veeam Backup & Replication creates and maintains the following types of backup files:

Full backup (.vbk) to store copies of full VM images
Backup increment (.vib or .vrb) to store incremental changes to VM images
Backup metadata (.vbm) to provide information on the backup job, VMs in the backup, number and structure of backup files, restore points, and so on. The metadata file facilitates import of backups or mapping of backup jobs to existing backups.

To back up VMs, you can use one of three available methods:

Foverver forward incremental backup
Forward incremental backup
Reverse incremental backup

Regardless of the method you use, the first run of a job creates a full backup of VM image. Subsequent job runs are incremental — Veeam Backup & Replication copies only those data blocks that have changed since the last backup job run. To keep track of changed data blocks, Veeam Backup & Replication uses its proprietary changed block tracking mechanism.

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