You can perform backups automatically based on the configuration for a hypervisor or VM group, or manually for a VM group or a specific VM. The backup process identifies and transfers only the allocated blocks—sections of the disk that actively contain data—to the backup storage. This method improves efficiency of backups and reduces storage usage.
The first backup of a VM is always a full backup. By default, all subsequent backups are incremental, capturing any changes to VM data since the last backup.
You can recover VM data, even when the most recent backup was incremental.
Backups run based on the following options:
-
Initial full backup: When you use Guided setup to set up the Virtualization solution, use the Back up now option to perform a backup for the default VM group.
-
Scheduled incremental backups: The backup plan that is assigned to a VM group includes a schedule for ongoing incremental backups. Those backups are performed automatically based on the schedule, without requiring any user action.
-
Manual backups: You can perform on-demand backups for a VM group or for a specific VM.
If backups cannot start immediately, the backup jobs are queued.
What Gets Backed Up
-
VMs (Windows and Linux, powered on or powered off)
-
VM templates
Considerations
-
Streaming, file system and application consistent, and crash consistent backups of the VMs are supported.
-
Proxmox node (host) must have the Virtual Server Agent package installed. The server will act as an access node for Proxmox VMs. For more information, see System Requirements for Proxmox VE Access Nodes.
-
To backup a VM, you must set the Proxmox node where the VM resides as an access node.
Changed block tracking for backups
With changed block tracking (CBT), incremental backups read only the blocks that changed since the previous backup. The behavior after a VM power cycle depends on the disk or storage type:
-
For QCOW2 disks, CBT information persists across VM power cycles. Incremental backups can continue to read only the changed blocks.
-
For other disk or storage types, CBT information does not persist across VM power cycles. After a power cycle, the next incremental backup reads the entire disk.
To use CBT for backups, you must configure the staging directory path. For more information, see Modify Settings for Proxmox VM Groups.