If an operating system bug, bad disk sector, or even certain superuser errors cause corruption to a file system, using multiple volumes can limit that damage to just one volume.
Some file systems do not support files larger than 2gb, so there is an option to set the maximum file size by splitting the image into multiplevolume files.
一些文件系统不支持大于2g的文件，因此，可以通过将映像分解到多个卷文件，从而设置最大文件大小。
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A single DCP may be stored in more than one medium (e.g., multiple hard disks). This file is used to identify the volume order in the series.