Hot Add Mode Working Incorrectly With Multiple VMs

Product version: 10.4

Last Updated: 11 October 2021


On a new installation of NAKIVO Backup & Replication, if the first job is a backup or replication job for multiple virtual machines in Hot Add mode, only one of the virtual machines is successfully processed in Hot Add mode. When transport mode is set to Auto, one VM succeeds with Hot Add mode while the others run in LAN mode. If transport mode is set to Hot Add, one VM succeeds with Hot Add mode while the others fail entirely with the following error:

Backup of the <VM name> VM has failed.

An internal error has occurred while backing up the <VM name> VM.


This is a result of VDDK-related behavior. When attempting to read multiple disks simultaneously, it fails and returns a timeout error. The vddk.cfg and debug.cfg files in the transporter VDDK subfolder must be manually configured in order to eliminate this issue.


To solve the problem, do the following: 

Locate the 3 vddk subfolders (vddk, vddk60, vddk67) within the transporter’s vddk path. In Linux, for example, this is located within /opt/nakivo/transporter/

Inside these folders, locate the respective vddk.cfg and debug.cfg files. Delete the “vix.DiskLib.transport.hotadd.NoNfcSession=1” line from each of the vddk.cfg and debug.cfg files.

Restart NAKIVO Backup & Replication services and re-test the issue.