code: func (c *sioClient) getGUID() (string, error) {
  	if c.sdcGUID == "" {
  		klog.V(4).Info(log("sdc guid label not set, falling back to using drv_cfg"))
  		cmd := c.getSdcCmd()
  		output, err := c.exec.Run(cmd, "--query_guid")
  		if err != nil {
  			klog.Error(log("drv_cfg --query_guid failed: %v", err))
  			return "", err
  		}
  		c.sdcGUID = strings.TrimSpace(string(output))
  	}
  	return c.sdcGUID, nil
  }
docs: // getGUID returns instance GUID, if not set using resource labels
  // it attempts to fallback to using drv_cfg binary