In this article, We are going to discuss the overview of Raw Device Mapping and difference between RDM virtual and Physical compatibility mode.
Raw device mapping (RDM) is providing direct access to a LUN on an ISCSi or fibre channel storage system for a virtual machine. The VM can directly access the storage device using RDM and the RDM contains metadata which controls the disk access to the physical device. For more information about RDM, take a look at VMware’s official Documentation.
Types of RDM Compatibility Mode
- Virtual compatibility mode allows an RDM to act exactly like a virtual disk file, including the use of snapshots.
- Physical compatibility mode allows direct access of the SCSI device for those applications that need lower level control.
Differences between Physical and Virtual RDM Modes
Lots of people wonder what is the differences between both types of Raw Device Mapping and when to use either of them. Below table provides some of the main differences between RDM virtual and physical compatibility mode.
An RDM provides a number of benefits, but it should not be used in every situation as there are lots of limitations that needs to be considered when it comes to daily operational tasks.