它使用缓冲区一次读取和写入8kB块.该数字相当随意，但是出于性能方面的考虑，在写入文件时使用512字节的倍数是有意义的，***是磁盘簇大小的倍数.对于大多数用途，8kB是合理的缓冲区大小.

That it uses a buffer to read and write 8kB blocks at once. The number is fairly arbitary, but for performance reasons it makes sense to use a multiple of 512 bytes when writing a file, and preferably a multiple of the disks cluster size. 8kB is a reasonable buffer size for most purposes.