But if the size of the file is known beforehand, persistent preallocation is the best route.
不过如果预先知道文件的大小时，持久化预分配是更好的选择。
2
Ext4 permits preallocation without doing this, which can improve the performance of some database and multimedia tools.
而ext4允许提前分配，无需进行上述操作，这能提高某些数据库和多媒体工具的性能。
3
Persistent preallocation If an application needs to allocate disk space before actually using it, most file systems do so by writing 0s to the not-yet-used disk space.