engine

type Interface interface {
	Close()
	// WriteAt writes block b to the File starting at byte offset off.
	// If only partial data is changed, offset so and eo are used to hint it.
	// WriteCallback cb is called with the number of bytes written and an error when the operation completes.
	WriteAt(z zone.Interface, b []byte, off int64, so, eo int, cb io.WriteCallback)
}