Additional Disk is seen on VMware UEB while Performing VMware Backups


Additional Disk is seen on VMware UEB while Performing VMware Backups



To make customers aware that additional disk/s might be seen when using VMware UEB and performing Backups of Virtual Machines (VMs) using ‘HotAdd’ Transport Method.


From Unitrends Version 7.1.0, to perform VMware Backups, HotAdd Transport Mode is supported on VMware UEBs. HotAdd is a VMware feature, where devices can be added ‘hot’ while a VM is running. Hence, while using the HotAdd Transport Method, disk/s would be added to the UEB itself only while the Backup/s is/are running. They would be removed once the backup is finished.

On the vSphere Client, in the ‘Recent Tasks’ section, once the backup is initiated, an additional event might be seen. It would have the Name - ‘Reconfigure virtual machine’ and the Target will be the name of the UEB VM.


Unitrends UEB creates a linked-clone VM, starting from the Backup snapshot and then reads the linked clone’s Virtual Disks for Backups. The disk/s associated with this linked clone are ‘HotAdd’ed to the UEB.

Unitrends uses VMware APIs to perform the VMware Backups. The VMware APIs create the temporary linked clone, hot attachment of the disks, perform the required Backup and then remove the temporary clone. While performing Backups using this Transport Method, the local LAN is not used.


This is an informative KB to explain customers that to leverage the use of HotAdd, the additional disk/s is/are added and removed by VMware APIs.

Third-Party Sources

VMware Documentation Center (Refer ‘HotAdd Transport’ Section) -


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