Unable to hot add disk while running backup from VEEAM - VMware vSphere
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Unable to hot add disk while running backup from VEEAM - VMware vSphere

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Article ID: 373502

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Updated On:

Products

VMware vSphere ESXi 8.0

Issue/Introduction

  • Backup operations fail when using Hot-Add transport mode.

  • Virtual Disk Development Kit (VDDK) logs (Located on the Veeam Proxy) display the following error:

    verbose -[####] [Originator@#### sub=transport] Released disk [DS NAME] VM NAME/VM NAME.vmdk at SCSI 0:1
verbose -[####] [Originator@#### sub=transport] SCSI hot-remove was successful for (####).
error -[####] [Originator@#### sub=transport] Mounting #### using transport hotadd failed : .
info -[####] [Originator@#### sub=transport] Deleted file C:\Users\username\AppData\Local\Temp\vmware-user\####-vm-####\hotadd\unmount.dat
info -[####] [Originator@#### sub=transport] Deleted directory C:\Users\username\AppData\Local\Temp\vmware-user\####-vm-####\hotadd
error -[####] [Originator@#### sub=transport] Cannot use mode hotadd to access  [DS NAME] VM NAME/VM NAME_1.vmdk: Cannot mount using this method. (Mounting #### using transport hotadd failed : .)
verbose -[####] [Originator@#### sub=transport] **** TryMode: Use mode nbdssl to access [DS NAME] VM NAME/VM NAME_1.vmdk

  • VMware vCenter tasks show the disk attachment as successful for the Veeam Proxy Virtual Machine. However the Windows OS fails to mount the volume when checked from Windows Disk management.

Environment

  • VMware vSphere ESXi 8.x

Cause

A communication breakdown between the legacy LSI Logic SAS storage controller and the Windows Guest OS driver stack. The hypervisor successfully attaches the hardware, but the OS fails to process the Plug-and-Play (PnP) interrupt required to mount the drive.

Resolution

Switch the disk controller type to VMware Paravirtual (PVSCSI). PVSCSI is the recommended default for Hot-Add transport as it is optimized for high-I/O environments and handles PnP events more reliably.

  1. Take a snapshot of the affected Veeam Proxy VM.

  2. Power off the affected Veeam Proxy VM.

  3. Navigate to vCenter, right-click the VM, and select Edit Settings.

  4. Click Add New Device and select SCSI Controller.

  5. Expand the new controller and set the Type to VMware Paravirtual.

  6. Modify existing virtual disks to use the new PVSCSI controller node. For detailed instructions, see Configuring disks to use VMware Paravirtual SCSI (PVSCSI) controllers

  7. Power on the VM.

  8. Verify stability and run a backup job to confirm functionality.

Additional Information

Contact Broadcom Support

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