磁鼓或磁盘表面上的一组磁道，可以并行地对它们进行读／写操作。 A group of tracks on a magnetic drum or on a magnetic disk all of which are read or written in parallel.
当顺序写操作超出文件原长度时，在文件末端另分配给该文件的空间量。 The amount of space to be allocated at the end of a file each time a sequential write exceeds the allocated length of the file.
