public function existsOnDFS( $filePath )
    {
        if ( file_exists( $this->makeDFSPath( $filePath ) ) )
        {
            return true;
        }

        // Verify that mount point is still there
        $filePathDir = substr( $filePath, 0, strpos( $filePath, '/' ) + 1 );
        $path = realpath( $this->getMountPoint() ). '/' . $filePathDir;
        if ( !file_exists( $path ) || !is_dir( $path ) )
        {
            throw new eZDFSFileHandlerBackendException( "NFS mount root $path not found" );
        }

        return false;
    }