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Which two solutions require Physical Mode Raw Device Mapping (RDM)? (Choose two.)
A. Direct access to the storage array device
B. Virtual Machine Snapshots
C. Hardware Acceleration
D. Guest Clustering across ESXi hosts
Correct Answer: AD
Explanation/Reference:
Explanation: A-) Note: RDM is not available for direct-attached block devices or certain RAID devices. You cannot map a disk partition as RDM. RDMs require the mapped device to be a whole LUN.(storage array device)
D-) Guest Clustering—– Physical mode is useful while running SAN management agents or other SCSI target-based software in the virtual machine.
Physical mode also allows virtual-to-physical clustering for cost-effective high availability.
Virtual Machine Snapshots are not available when the RDM is used in physical compatibility mode.
You can use this mode for Physical-to-virtual clustering and cluster-across-boxes.
VMFS5 supports greater than 2 TB disk size for RDMs in physical compatibility mode only. These restrictions apply:
You cannot relocate larger than 2 TB RDMs to datastores other than VMFS5.
You cannot convert larger than 2 TB RDMs to virtual disks, or perform other operations that involve RDM to virtual disk conversion. Such operations include cloning.
FAQ: https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1037959