VCP550 · Question #31
Which feature requires an administrator to configure an RDM with Virtual Compatibility Mode?
The correct answer is B. Virtual Machine Snapshots. RDM Virtual Compatibility Mode wraps the raw LUN in a VMFS-managed descriptor layer, which is required to enable virtual machine snapshots. Physical Compatibility Mode bypasses this layer and does not support snapshots.
Question
Which feature requires an administrator to configure an RDM with Virtual Compatibility Mode?
Options
- AvMotion
- BVirtual Machine Snapshots
- CHigh Availability
- DN-port ID Virtualization
How the community answered
(45 responses)- A2% (1)
- B91% (41)
- C2% (1)
- D4% (2)
Why each option
RDM Virtual Compatibility Mode wraps the raw LUN in a VMFS-managed descriptor layer, which is required to enable virtual machine snapshots. Physical Compatibility Mode bypasses this layer and does not support snapshots.
vMotion is supported with both Virtual and Physical Compatibility Mode RDMs, so neither mode is exclusively required for live migration.
Virtual Compatibility Mode presents the RDM through a VMFS disk descriptor, allowing the snapshot subsystem to create and chain delta disks on top of the base mapping; Physical Compatibility Mode provides direct SCSI passthrough without a descriptor layer, so no snapshot delta can be inserted.
High Availability operates at the cluster failover level and does not depend on the RDM compatibility mode configured for a VM's disks.
N-Port ID Virtualization requires Physical Compatibility Mode RDMs because NPIV relies on direct SCSI command passthrough, making Virtual Compatibility Mode incompatible with NPIV.
Concept tested: RDM Virtual Compatibility Mode enabling virtual machine snapshots
Source: https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.storage.doc/GUID-9E206B41-4B2D-48F0-85A3-B8715D78E846.html
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