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。
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.
持久性预分配如果一个应用程序需要在实际使用磁盘空间之前对它进行分配，大部分文件系统都是通过向未使用的磁盘空间写入0来实现分配。
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