When a virtual machine interacts with persistent thick virtual disks stored on a traditional Fibre Channel storage array, which two actions are always taken by the VMkernel? (Choose two.)
A.
The file corresponding to the virtual machine is located on the VMFS datastore using NPIV.
B.
Correlate the blocks requested by the virtual machine with the actual blocks on the array.
C.
Send the I/O request through the device driver to the physical HBA or software FCoE adapter.
D.
Place an atomic lock on the metadata database for the VMFS volume.
http://pubs.vmware.com/vsphere-51/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-51-storage-guide.pdf
How Virtual Machines Access Data on a Fibre Channel SAN
ESXi stores a virtual machine’s disk files within a VMFS datastore that resides on a SAN storage device.
When virtual machine guest operating systems issue SCSI commands to their virtual disks, the SCSI virtualization
layer translates these commands to VMFS file operations.
When a virtual machine interacts with its virtual disk stored on a SAN, the following process takes place:
1 When the guest operating system in a virtual machine reads or writes to a SCSI disk, it issues SCSI
commands to the virtual disk.
2 Device drivers in the virtual machine’s operating system communicate with the virtual SCSI controllers.
3 The virtual SCSI controller forwards the command to the VMkernel.
4 The VMkernel performs the following tasks.
a Locates the file in the VMFS volume that corresponds to the guest virtual machine disk.
b Maps the requests for the blocks on the virtual disk to blocks on the appropriate physical device.
c Sends the modified I/O request from the device driver in the VMkernel to the physical HBA.
5 The physical HBA performs the following tasks.
a Packages the I/O request according to the rules of the FC protocol.
b Transmits the request to the SAN.
6 Depending on a 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
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Do you have diagram to explain this order?
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“Sends the modified I/O request from the device driver in the VMkernel to the physical HBA.”
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I think, strictly speaking, answer C is not correct, beacause software FCoE adapter is not appeared as a vmhba in the ESXi host. If using “the physical HBA or hardware FCoE adapter, answer C is totally correct.
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I think B&C
VMKernel will map between VM blocks and Physical Blocks
VMKernel must use device driver to talk to physical hardware. Bit confusing because host based RAID adapters are not supported but host based HBA devices are.
D is bogus
A NPIV is a task/property of FC storage not VMKernel
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