This knowledge base article addresses the issue of encountering the alert message "One or more Disks attached to the VM are not accessible at the moment" within the BDRShield application. The article provides insights into the potential causes of this alert and offers solutions to resolve it effectively.

The alert "One or more Disks attached to the VM are not accessible at the moment" is typically triggered when the Hyper-V virtual machines (VMs) cannot be accessed or are not found during backup operations. The following reasons might contribute to this issue:

1. VM with No Attached Disks:

A VM might not have any virtual hard disks (VHD/VHDX) attached to it, causing the backup process to fail.

2. VM Configured via Quick VM Recovery:

1. VMs configured for backup using VembuBDR's Quick VM Recovery option can result in backup failures along with the stated alert.
   
2. VMs having disks sourced from any virtual drive can also lead to backup issues.
   

3. Cluster VM Owner and CSV Disk Owner Conflict:

In cases where the cluster VM owner and the CSV (Cluster Shared Volume) disk owner have Maintenance mode turned ON and are different, this conflict can contribute to the alert.

To address the "One or more Disks not Accessible" issue, follow these steps:

1. Verify VM Disk Availability:

Confirm whether the virtual disks attached to the VM are available and accessible.

2. Adjust Disk Location:

If the VM's disks are located in a virtual drive, consider changing the disk storage location to local, SMB, or CSV storage.

3. Resolve VM Owner and CSV Disk Owner Conflict:

 If the VM owner and CSV disk owner differ and the Maintenance mode is ON, either turn off the maintenance mode or ensure that both VM owner and CSV disk owner are the same.