ESXi Host Disconnects When Attempting to Resize Disk of VM through pyvmomi

Products

• VMware vCenter Server
• VMware vSphere ESX 7.x
• VMware vSphere ESX 8.x
• VMware vSphere ESXi
• VMware vSphere ESXi 7.0
• VMware vSphere ESXi 8.0
• VMware vCenter Server 7.0
• VMware vCenter Server 8.0

Issue/Introduction

While attempting to extend the disk of a Virtual Machine (vm) using PyVmomi, the task shows as failed in vCenter but completes the disk resize.

The Virtual Machine's host disconnects.

The Reconfigure Virtual Machine task shows as failed with "An error occurred while communicating with the remote host." on vCenter.

Reconfiguration of Virtual Machine functions as expected through manual execution in the GUI.

Environment

• VMware vCenter Server 7.x
• VMware vCenter Server 8.x
• VMware vSphere ESXi 7.x
• VMware vSphere ESXi 8.x

 

Cause

Occurs if the reconfiguration task calls for a new Virtual Disk device instead of accessing the Virtual Disk that already exists on the vm.

Resolution

To resolve this issue, make sure to call the appropriate Virtual Disk device when setting the spec for the reconfigure task. Below is an example of what that looks like.

def modify_vm_disk(new_vm, disk_size_gb):

    content = service_instance.content

    new_vm_name = None

    disk_spec = None

    vm_view = content.viewManager.CreateContainerView(content.rootFolder, [vim.VirtualMachine], True)

    vm_list = vm_view.view

    disk_to_resize = None

       

    for vm in vm_list:

        if vm.name == new_vm:

            for device in vm.config.hardware.device:

                if isinstance(device, vim.vm.device.VirtualDisk):

                    if device.deviceInfo.label == "Hard disk 1":

                        disk_to_resize = device

                        break

            new_vm_name = vm

            spec = vim.vm.ConfigSpec()

            spec_deviceChange_0 = vim.vm.device.VirtualDeviceSpec()

            spec_deviceChange_0.device = disk_to_resize

            spec_deviceChange_0.device.capacityInKB = disk_size_gb * 1024 * 1024

            spec_deviceChange_0.operation = vim.vm.device.VirtualDeviceSpec.Operation.edit

            spec.deviceChange = [spec_deviceChange_0]                      

            task = new_vm_name.Reconfigure(spec=spec)

Additional Information

For more information on using vSphere SDKs and pyVmomi, refer to the Broadcom Developer Portal, pyVmomi download page and pyVmomi community samples.