About VMware raw device mapping (RDM)
VMware raw device mapping mode (RDM) allows a virtual machine to directly access physical disks. With raw device mapping, a VMware virtual machine can use large storage devices such as disk arrays. Access to the data on an RDM disk is faster than to a fully virtualized disk (vmdk file). An RDM disk can be locally attached to the ESX server or configured on a Fibre Channel SAN.
NetBackup supports the disk arrays that are configured on a virtual machine as RDMs.
Note:
NetBackup cannot back up the RDM by means of a VMware backup host.
For notes and restrictions on NetBackup support for VMware RDM, see the following Veritas tech note:
Support for NetBackup in virtual environments
http://www.veritas.com/docs/000006177