Try this. No guarentees as it is quite hard to contrive a test scenario.

Adjust the drive letter in the call to createFile() to suit.

#! perl -slw
use strict;
use Win32API::File; ## Hacked to export everything 
use Win32::API::Prototype;

ApiLink 'Kernel32', q[BOOL FlushFileBuffers( HANDLE hFile )] 
    or die $^E;


my $devHandle = createFile( '//./C:', 'wke' );
$devHandle == -1 and die $^E;
FlushFileBuffers( $devHandle ) or die $^E;
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