Microsoft Hyper-V

Zmanda Pro offers a seamless way to safeguard your Hyper-V VMs. Here's what you need to know.

Backup Modes:

Zmanda Pro provides three Hyper-V backup modes to suit your specific needs:

  1. Latest VM State (Changed Block Tracking): This efficient mode leverages WMI and RCT (Changed Block Tracking) technology. It's compatible with Hyper-V on Windows Server 2016 or later and Windows 10 or later. Zmanda Pro integrates with Hyper-V to capture only the latest changes to your VMs, minimizing storage usage.

  2. Latest VM State (Standard): Similar to the first mode, this option utilizes WMI and RCT for compatibility with the same Hyper-V versions. Zmanda Pro captures the latest VM snapshot data, ensuring a recent backup point.

  3. All VM Snapshots: This comprehensive mode utilizes VSS (Volume Shadow Copy Service) technology. It works with all Hyper-V versions on Windows Server, including the latest Windows Server 2022. This option captures all existing VM snapshots, providing a complete backup history.

Zmanda Pro lets you to choose individual VMs for backup or select "All virtual machines" for comprehensive protection.

Understanding Consistency:

Maintaining a consistent VM state during backups is crucial. Zmanda Pro employs various methods depending on your guest OS setup:

  • Guest OS with Integration Services: If your guest OS has the necessary Hyper-V integration services, Zmanda Pro coordinates with the host to create a VSS snapshot within the guest VM. This snapshot is then backed up, ensuring application consistency (crash-consistent or application-consistent depending on guest OS support).

  • Guest OS without Integration Services (Server 2012 R2 or later): In this scenario, Hyper-V takes a checkpoint of the VM. Zmanda Pro backs up this checkpoint and then removes it, minimizing disruption to the guest OS (crash-consistent).

  • Guest OS without Integration Services (Older Than Server 2012 R2): Here, Zmanda Pro pauses the VM, Windows takes a VSS snapshot of Hyper-V's files, the VM resumes, and the snapshot is backed up. This approach might cause a brief interruption to the guest OS (crash-consistent).

Replica VMs:

Zmanda Pro allows you to back up your VMs from either the primary or replica host when using Hyper-V replication. Backups from the primary host can be application-consistent (if guest integration services allow) or crash-consistent. Backups from the replica host are always crash-consistent since the VM isn't running for guest integration.

Important Considerations:

  • Pass-through Disks: Hyper-V pass-through disks (physical disks attached directly to the guest VM) aren't directly supported in backups. To address this:

    • Install Zmanda Pro Agent inside the guest VM for file-level backup (requires an additional Device license).

    • Convert pass-through disks to regular disks containing .vhd or .vhdx files.

  • Restoring from Hyper-V Checkpoints:

    • Granular file restore from Hyper-V checkpoints requires Zmanda Pro version 22.12.6 or later.

    • Backups preserve Hyper-V checkpoints within the storage vault.

    • Use the "Import Virtual Machine" wizard in Hyper-V Manager to restore the entire VM, including selecting the desired checkpoint.

    • Granular restore only works with the base checkpoint (vhdx file), not future checkpoints (avhdx files). Restore the entire vhdx/avhdx set for individual file recovery from later checkpoints.

  • Importing Running VMs:

    • When importing a running VM using the Hyper-V Manager wizard, incompatibility issues might arise if the target hypervisor has a significantly different CPU architecture.

    • To prevent issues:

      • Use the "Power off" option instead of "Shut down" during import.

      • Re-import the VM from saved disk files without including the RAM running state.

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