I think the last argument is missing a file extension, as you found the other day.

With `size` modified to be an integer:
```
[obnode0] Running 'pre-boot' VM customizations...
A customization command failed:

["storageattach", :id, "--storagectl", "SATA Controller", "--port", 1, "--device", 0, "--type", "hdd", "--medium", "/tmp/obnode_extradisc"]

The following error was experienced:

#<Vagrant::Errors::VBoxManageError: There was an error while executing `VBoxManage`, a CLI used by Vagrant
for controlling VirtualBox. The command and stderr is shown below.

Command: ["storageattach", "3be09702-893d-447c-a608-203ed839dc9a", "--storagectl", "SATA Controller", "--port", "1", "--device", "0", "--type", "hdd", "--medium", "/tmp/obnode_extradisc"]

Stderr: VBoxManage: error: Could not find file for the medium '/tmp/obnode_extradisc' (VERR_FILE_NOT_FOUND)
VBoxManage: error: Details: code VBOX_E_FILE_ERROR (0x80bb0004), component Medium, interface IMedium, callee nsISupports
VBoxManage: error: Context: "OpenMedium(Bstr(pszFilenameOrUuid).raw(), enmDevType, enmAccessMode, fForceNewUuidOnOpen, pMedium.asOutParam())" at line 178 of file VBoxManageDisk.cpp
VBoxManage: error: Invalid UUID or filename "/tmp/obnode_extradisc"
>

Please fix this customization and try again.
```