VMware vSphere SDKs and Tools 7.0

8.0 7.0 6.7 6.5

Using the VirtualMachineConfigInfo

A backup application can also use information contained in a
VirtualMachineConfigInfo
. If at backup time you preserve all the
VirtualMachineConfigInfo
 details that describe the virtual machine, you can transfer much of this information into a
VirtualMachineConfigSpec
 to create a virtual machine at restore time. However, some of the information in
VirtualMachineConfigInfo
 is not needed, and if used in the
Spec
, virtual machine creation can fail. For example, a
VirtualMachineConfigSpec
 that contains information about so called “Default Devices” usually fails. The list of default devices includes: 
vim.vm.device.VirtualIDEController
vim.vm.device.VirtualPS2Controller
vim.vm.device.VirtualPCIController
vim.vm.device.VirtualSIOController
vim.vm.device.VirtualKeyboard
vim.vm.device.VirtualVMCIDevice
vim.vm.device.VirtualPointingDevice
However, other controllers and devices must be explicitly included in the
VirtualMachineConfigSpec
.
Some information about devices is unneeded and can cause problems if supplied. Each controller device has its
vim.vm.device.VirtualController.device
 field, which is an array of devices that report to the controller. The server rebuilds this list when a virtual machine is created, using the (negative) device key numbers supplied as a guide. The relationship between controller and device must be preserved using negative key numbers in the same relationship as in the hardware array of
VirtualMachineConfigInfo
.
The parent property for virtual disk backing information must be set to null. In the sample code for creating a virtual machine, find
vim.vm.device.VirtualDisk.FlatVer2BackingInfo
 under SCSI disk one and SCSI disk two. The null setting is required because the pre-backup snapshot causes the parent property to be populated with a reference to the base disk.
One other configuration needs substitution.
VirtualMachineConfigInfo
 contains the
cpuFeatureMask
, field, which is an array of
HostCpuIdInfo
. The array entries must be converted to
ArrayUpdateSpec
 entries containing the
VirtualMachineCpuIdInfoSpec
 along with the “operation” field, which must contain the value
ArrayUpdateOperation::add
. The
VirtualMachineCpuIdInfoSpec
 also contains a
HostCpuIdInfo
 array that you can copy from the
cpuFeatureMask
 array in
VirtualMachineConfigInfo
. These items are not reflected in the sample code. Everything else can be copied intact from
VirtualMachineConfigInfo
 data.
To summarize: when creating a virtual machine in which to restore virtual disk:
  • Exclude default devices, and
    VirtualController.device
    , from the
    VirtualMachineConfigSpec
    .
  • Set the parent virtual disk backing information (
    VirtualDisk.FlatVer2BackingInfo
    ) to null.
  • Convert
    HostCpuIdInfo
     array entries to
    ArrayUpdateSpec
    , insert
    ArrayUpdateOperation::add
    , and copy the
    HostCpuIdInfo
     array from
    cpuFeatureMask
     into
    VirtualMachineConfigInfo
    .

Content feedback and comments