In VMware vSphere, the virtual disk of a virtual machine consists of two main files: the descriptor file and the flat file.

1. Descriptor File (VMName.vmdk): The descriptor file (with a .vmdk extension) is a small text file that contains metadata and information about the virtual disk, such as its geometry, type (thin or thick provisioned), and the path to the associated flat file. It acts as a pointer to the flat file, describing how the virtual disk is structured.
2. Flat File (VMName-flat.vmdk): The flat file (with a -flat.vmdk extension) is the actual data file for the virtual disk. It stores the contents of the virtual disk, including the operating system, applications, and user data.

When a virtual machine is created or a virtual disk is added to a virtual machine, vSphere creates the descriptor file with the necessary metadata and links it to a new or existing flat file. The descriptor file does not contain any actual data but points to the flat file where the data is stored.

To map the descriptor file with the flat file, you typically don’t need to perform manual mapping as vSphere handles this internally. The association between the descriptor and flat files is maintained by vSphere and is transparent to the virtual machine administrator.

However, there might be situations where you need to locate the descriptor file associated with a specific flat file or vice versa. You can use the following methods to find this information:

1. vSphere Client: In the vSphere Client, you can browse the datastore where the virtual machine files are stored. The descriptor file (VMName.vmdk) and the flat file (VMName-flat.vmdk) are visible in the datastore browser.
2. PowerCLI: If you prefer using PowerShell and VMware PowerCLI, you can use the Get-HardDisk cmdlet to retrieve information about virtual disks associated with a virtual machine. This cmdlet will show you the file names and paths of the descriptor and flat files.

# Connect to vSphere
Connect-VIServer -Server vCenter_Server_or_ESXi_Host -User username -Password password

# Get the virtual machine object
$VM = Get-VM -Name "YourVirtualMachine"

# Get information about the virtual disks
$VirtualDisks = Get-HardDisk -VM $VM

# View the file names and paths of the descriptor and flat files
foreach ($VirtualDisk in $VirtualDisks) {
    Write-Host "Descriptor File: $($VirtualDisk.Filename)"
    Write-Host "Flat File: $($VirtualDisk.FileNameWithExtension)"
}

# Disconnect from vSphere
Disconnect-VIServer -Server * -Confirm:$false

Please note that manually modifying or moving virtual disk files outside of vSphere is not recommended, as it can lead to data corruption and virtual machine issues. Always perform disk management tasks through the vSphere Client or PowerCLI to ensure proper maintenance and integrity of your virtual machine storage.