Fixing the NBD_ERR_GENERIC error with ESXi and VCBMounter

When dealing with ESXi free, VSquare will not use managed APIs but instead resort to the VMware vcbmounter command. Sometimes, with some specific virtual machines you may receive an error similar to the following one :

[00][machine_name] *************************************************[2014-11-04 14:02:44.727 'vcbMounter' 14672 error] Error: Failed to open the disk: NBD_ERR_GENERIC

This error is caused by the "-m NBD" switch used by VSquare and ca be easily fixed following the steps below :

• Power down the virtual machine.
• Unregistered the virtual machine from vCenter Server inventory.
• Changed the following line in the .vmx file:
  disk.enableUUID = "TRUE" to "FALSE"
• Save the .vmx file.
• Re-registered the virtual machine.

Alternatively, If you prefer, you can change the vcbmounter command used by VSquare and change the "-m NDB" switch to reflect the transport mode you wish to use :

• Stop Vsquare Backup Service
• Go to VSquare Data folder (usually under the VSquare Backup installation folder)
• Open the file "VSquare.DataModel.Variable.xml" with an editor like notepad
• Inside the file, locate the word "vcbmounter". It appears only once in the file
• Inside the located Value tag, change the vcbmounter command to suit your needs.
• Save the XML file and start VSquare Backup service

These workarounds are not required for any fully licensed VMware ESXi since VSquare will use a full API mode to backup and will be able to set the flag automatically without turn-on/turn-off cycle.

Further reading:

• Virtual Disk Development Kit library reports the error: Failed to open NBD extent, NBD_ERR_GENERIC (1022543)
• Error: Failed to open the disk: NBD_ERR_GENERIC