pyvmomi no thin provision when cloning

Question

I am trying to clone a VM in VMWare using pyVmomi.

However, I am having trouble getting thin provisioning for the disk.

Here are the portions of the code I believe are relevant for reproducing the issue.

def find_disk(vm,index):
"""Return the disk of the given index in the vm"""
    i=0
    for device in vm.config.hardware.device:
        if hasattr(device.backing,"fileName"):
            if i==index:
                return device
            else:
                i +=1

def disk_controller(vm):
    """Return the first disk controller for the given vm"""
    for device in vm.config.hardware.device:
        if isinstance(device,vim.vm.device.VirtualSCSIController):
            return device

# retrieve the template
template=retrieve_template_vm()
disk=find_disk(template,0)
controller=disk_controller(template)    
## Create the the clonespec
clonespec=vim.vm.CloneSpec()    
# Define the disk-change specification for changing the template's hard disk
disk_spec=vim.vm.device.VirtualDeviceSpec()
disk_spec.operation=vim.vm.device.VirtualDeviceSpec.Operation.edit
disk_spec.device=disk
disk_spec.device.controllerKey=controller.key
disk_spec.device.capacityInKB=60*1024*1024
disk_spec.device.backing.thinProvisioned=True
clonespec.config=vim.vm.ConfigSpec(numCPUs=2,memoryMB=4096,deviceChange=[disk_spec])
...
# Make other changes to the clone spec, such as setting datastore and cluster
...    
template.Clone(folder=FOLDER,name=NEW_VM_NAME,spec=clonespec)

Everything seems to be working with the cloning EXCEPT the thin provisioning of the disk. When I print out the clonespec right before cloning, I see the following (note the thinProvisioned = true portion):

     (vim.vm.device.VirtualDeviceSpec) {
        dynamicType = <unset>,
        dynamicProperty = (vmodl.DynamicProperty) [],
        operation = 'edit',
        fileOperation = <unset>,
        device = (vim.vm.device.VirtualDisk) {
           dynamicType = <unset>,
           dynamicProperty = (vmodl.DynamicProperty) [],
           key = 2000,
           deviceInfo = (vim.Description) {
              dynamicType = <unset>,
              dynamicProperty = (vmodl.DynamicProperty) [],
              label = 'Hard disk 1',
              summary = '52,428,800 KB'
           },
           backing = (vim.vm.device.VirtualDisk.FlatVer2BackingInfo) {
              dynamicType = <unset>,
              dynamicProperty = (vmodl.DynamicProperty) [],
              fileName = '[SOME_IDENTIFIER] TEMPLATE_NAME/template_vm_name.vmdk',
              datastore = 'vim.Datastore:datastore-38',
              backingObjectId = '26-2000-0',
              diskMode = 'persistent',
              split = false,
              writeThrough = false,
              thinProvisioned = true,
              eagerlyScrub = true,
              uuid = '6000C293-7bc0-d8b5-9258-661c0368f67d',
              contentId = '2a9b1883eb64e83b2a02d32225cead08',
              changeId = <unset>,
              parent = <unset>,
              deltaDiskFormat = <unset>,
              digestEnabled = false,
              deltaGrainSize = <unset>
           },
           connectable = <unset>,
           slotInfo = <unset>,
           controllerKey = 1000,
           unitNumber = 0,
           capacityInKB = 62914560,
           capacityInBytes = 53687091200,
           shares = (vim.SharesInfo) {
              dynamicType = <unset>,
              dynamicProperty = (vmodl.DynamicProperty) [],
              shares = 1000,
              level = 'normal'
           },
           storageIOAllocation = (vim.StorageResourceManager.IOAllocationInfo) {
              dynamicType = <unset>,
              dynamicProperty = (vmodl.DynamicProperty) [],
              limit = -1,
              shares = (vim.SharesInfo) {
                 dynamicType = <unset>,
                 dynamicProperty = (vmodl.DynamicProperty) [],
                 shares = 1000,
                 level = 'normal'
              },
              reservation = 0
           },
           diskObjectId = '26-2000',
           vFlashCacheConfigInfo = <unset>
        },
        profile = (vim.vm.ProfileSpec) []

When I check the disk specs after cloning via the GUI, The hard disk details say "Thick Provision Lazy Zeroed".

Does anybody know why the new disks are not being thin-provisioned, and what should be done instead?

Edit When I first wrote this question, I left out the crucial line of code disk_spec.device.backing.thinProvisioned=True, which is now included above. This was always included in my real script already, so the problem still remains.

UPDATE By migrating the template to a thin-provisioned disk, a thin provisioned disk can be made for the resulting VM. However, the issue with the code still remains as it seems as though it should work.

I believe the problem may be solved adding line(s) similar to:

disk_spec.fileOperation="create"

This should specify a change to device_spec.backing will be made also, but in my trials this caused the cloning to break. If anybody knows how to make the above work it would still be greatly appreciated.

user7893999 user7893999 · Accepted Answer · 2018-01-03T10:20:23

The VirtualMachineRelocateTransformation is depricated. Please use vim.vm.RelocateSpec.DiskLocator instead:

disk_locator = vim.vm.RelocateSpec.DiskLocator()
disk_locator.diskBackingInfo = vim.vm.device.VirtualDisk.FlatVer2BackingInfo()
disk_locator.diskBackingInfo.eagerlyScrub = True
disk_locator.diskBackingInfo.thinProvisioned = False
for device in template_vm.config.hardware.device:
    if hasattr(device.backing, 'fileName'):
        disk_locator.diskId = device.key
        break
disk_locator.datastore = datastore_object
relospec.disk.append(disk_locator)

Example above clones VM and changes disk type to thick provisioned eager zeroed.

pyvmomi no thin provision when cloning

2 Answers