Sometimes, backup at a hypervisor level is not possible because of virtualization product or Acronis Backup limitations.

Agent for VMware cannot back up fault tolerant virtual machines.
Agent for VMware cannot back up Raw Device Mapping (RDM) disks in physical compatibility mode and independent disks.
Microsoft Hyper-V does not provide control over pass-through disks to a host system. As a result, the Microsoft Software Shadow Copy provider cannot provide Agent for Hyper-V with snapshots of pass-through disks.

To overcome these limitations, use backup from inside a guest OS. Using this method, you can also:

Execute pre/post backup or pre/post data capture commands within the guest operating system.
Back up individual files and folders of a virtual machine.
Recover files to a virtual machine's file system.
Back up a guest system stored on a logical volume to be able to recover the machine to a different platform.
Use the backup and recovery options that are not effective for backup at a hypervisor level.

For more details, please see the following sections:

Limitations related to VMware vSphere 6.5

Encrypted virtual machines (introduced in VMware vSphere 6.5)
- Encrypted virtual machines are backed up in an unencrypted state. If encryption is critical to you, enable encryption of backups when creating a backup plan.
- Recovered virtual machines are always unencrypted. You can manually enable encryption after the recovery is complete.
- If you back up encrypted virtual machines, we recommend that you also encrypt the virtual machine where Agent for VMware is running. Otherwise, operations with encrypted machines may be slower than expected. Apply the VM Encryption Policy to the agent's machine by using vSphere Web Client.
Secure Boot (introduced in VMware vSphere 6.5)
Secure Boot is disabled after a virtual machine is recovered as a new virtual machine. You can manually enable this option after the recovery is complete.