VMware SCSI requirements for application quiesce on Windows
For a snapshot that quiesces an application on a Windows VM, VMware imposes the following disk requirements:
The VM's disks must be SCSI, not IDE.
The SCSI disks on the VM's SCSI controller must not occupy more than half of the total number of slots in the controller. Since the controller has a total of 15 slots, the number of disks in that controller must not exceed 7.
If these conditions are not met and the NetBackup VMware policy enables the option, the backup may fail with status code 156.
For more information on this VMware requirement, refer to the information on Windows Backup Implementations on the VMware docs web site.