# Unsupported disk types

**When performing a virtual machine backup (agentless), Xopero ONE relies on the hypervisor's snapshot mechanism to ensure data consistency. Certain disk types are architecturally excluded from snapshots by the hypervisor itself, which means they cannot be included in a standard VM-level backup.**

***

## Excluded Hyper-V disks

The following disk modes do not support snapshots and cannot be backed up:

* **Pass-through disks** — these disks are directly attached to the physical storage and are bypassed by the **Hyper-V** checkpoint (snapshot) mechanism.

{% hint style="info" %}
This is not a limitation of **Xopero ONE**, but a characteristic of how these virtual disks are designed to operate within **VMware** and **Hyper-V** environments. Because a snapshot cannot be created, **Xopero ONE** cannot guarantee data consistency or access data during a host-level task.
{% endhint %}

***

## Recommended workaround

If you need to protect data on pass-through disks, you can use the following method:

1. Install the **Xopero ONE Backup\&Recovery Agent** directly within the virtual machine’s guest operating system.
2. Configure a file or image-level backup task with the installed agent.

By using an in-guest agent, **Xopero ONE** utilizes the internal VSS (**Windows**) or live-read (**Linux**) mechanisms to capture the data, effectively bypassing the hypervisor's snapshot limitations.