FSType     string
	RootDisk   bool
	Healing    bool
	Scanning   bool
	Endpoint   string
	MountPath  string
	ID         string
	Rotational bool
	Metrics    DiskMetrics
	Error      string // carries the error over the network
}

// DiskMetrics has the information about XL Storage APIs
// the number of calls of each API and the moving average of
// the duration of each API.
type DiskMetrics struct {