When writes from a virtual machine are delivered to a Fibre Channel Storage
Array, which of the following actions is taken by the VMkernel (Choose Three)?
A.
The file corresponding to the virtual machine is located on the VMFS datastore
B.
The request for blocks on the virtual disk is mapped to blocks on the appropriate
physical device
C.
The modified I/O request is sent from the device driver to the physical HBA
D.
The commands are forwarded by the virtual SCSI Controller
E.
The I/O request is converted from binary data form to optical form
Explanation:
Fibre Channel SAN Configuration Guide ESX Server 3.5, ESX Server 3i version 3.5
VirtualCenter 2.5, page 40.
When a virtual machine interacts with a SAN, the following process takes place:
When the guest operating system in a virtual machine needs to read or write to SCSI
disk, it issues SCSI commands to the virtual disk.
Device drivers in the virtual machine’s operating system communicate with the virtual
SCSI controllers. VMware ESX Server supports two types of virtual SCSI controllers:
BusLogic and LSILogic.
The virtual SCSI Controller forwards the command to the VMkernel.
The VMkernel:
Locates the file in the VMFS volume that corresponds to the guest virtual machine disk.
Maps the requests for the blocks on the virtual disk to blocks on the appropriate physical
device.
Sends the modified I/O request from the device driver in the VMkernel to the physical
HBA (host HBA).
The host HBA:
Converts the request from its binary data form to the optical form required for
transmission on the fibre optic cable.
Packages the request according to the rules of the FC protocol.
Transmits the request to the SAN.
Depending on which port the HBA uses to connect to the fabric, one of the SAN switches
receives the request and routes it to the storage device that the host wants to access.
