Home » VMware » VCP550D » Which two virtual disk types are supported with FT?
An administrator is planning a vSphere Fault Tolerance implementation for 6 virtual machines. Which two virtual disk types are supported with FT? (Choose two.)
A. Raw Device Mapped LUN configured for Virtual Compatibility Mode
B. Raw Device Mapped LUN configured for Physical Compatibility Mode
C. Virtual disk thick provisioned, eager zeroed
D. Virtual disk thick provisioned, lazy zeroed
Correct Answer: AC
Explanation/Reference:
Explanation:
Fault Tolerance (FT) in VMware vSphere provides continuous availability for a virtual machine (VM) in the event of server failures by creating a live shadow instance of a virtual machine that is always up-to-date with the primary virtual machine. In the event of a hardware failure, FT automatically triggers failover to the secondary VM. After a failover, FT automatically creates a new, secondary virtual machine to provide continuous protection for the VM.
FT requires that multiwriter mode is possible on the VMDK to enable both the primary and secondary FT VMs to access the same disk. To use disks in multiwriter mode, the format must be Thick Provision Eager Zeroed or a Raw Device Mapped (RDM) LUN configured for Virtual Compatibility Mode.
FT Virtual Machine Requirements:
Virtual machines must be stored in virtual RDM or virtual machine disk (VMDK) files that are thick provisioned. If a virtual machine is stored in a VMDK file that is thin provisioned and an attempt is made to enable Fault Tolerance, a message appears indicating that the VMDK file must be converted. To perform the conversion, you must power off the virtual machine.
Incorrect Answers:
B: A Raw Device Mapped (RDM) LUN configured for Physical Compatibility Mode is not supported. An RDM LUN must be configured for Virtual mode. Therefore, this answer is incorrect.
D: Thick Provision Lazy Zeroed creates a virtual disk in a default thick format. Space required for the virtual disk is allocated when the disk is created. Data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine. Thick Provision Lazy Zeroed disks do not support Fault Tolerance. Therefore, this answer is incorrect.
References:
https://pubs.vmware.com/vsphere-55/index.jsp#com.vmware.vsphere.avail.doc/GUID-83FE5A45-8260-436B-A603-B8CBD2A1A611.html
