- `disk_size` (uint) - The size, in megabytes, of the hard disk to create for the VM. By default, this is 40 GB. - `use_legacy_network_adapter` (bool) - If true use a legacy network adapter as the NIC. This defaults to false. A legacy network adapter is fully emulated NIC, and is thus supported by various exotic operating systems, but this emulation requires additional overhead and should only be used if absolutely necessary. - `differencing_disk` (bool) - If true enables differencing disks. Only the changes will be written to the new disk. This is especially useful if your source is a VHD/VHDX. This defaults to false. - `use_fixed_vhd_format` (bool) - If true, creates the boot disk on the virtual machine as a fixed VHD format disk. The default is false, which creates a dynamic VHDX format disk. This option requires setting generation to 1, skip_compaction to true, and differencing_disk to false. Additionally, any value entered for disk_block_size will be ignored. The most likely use case for this option is outputing a disk that is in the format required for upload to Azure.