Attaching RDM to a virtual machine
In many environments, there will be requirements or special cases that warrant the use of raw device mappings (RDM). The use of RDMs allows the guest operating system running in a VM to create its native filesystem on a LUN device. The benefits of using RDMs have been outlined in the vSphere 5.1 Storage guide:
RDMs can be presented to a VM in two compatibility modes:
Physical compatibility: In this mode all of the SCSI commands except the REPORT LUNs command is sent to the device directly. Therefore, this mode is also referred to as a Passthrough mode.
Virtual compatibility: In this mode only the READ and WRITE commands are sent to the device. In this mode the RDM will be compatible with most of the tasks that can be performed on a traditional VMDK.
In this recipe of the chapter, we will learn how to attach a raw device mapping to a virtual machine...
