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delphidiskioctl

How can a volume exist on more than one physical disk?

Here they say that calling DeviceIoControl with IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS control code, "retrieves the physical location of a specified volume on one or more disks." But from my 25 years of using compuers I know that a physical disk can have one or more volumes, not the other way around. I can't even imagine how a volume can exist on multiple physical disks. So, the question is, which are the cases when a volume exists on multiple disks?

Solution

  • Spanned Volume

    A spanned volume combines areas of unallocated space from multiple disks into one logical volume, allowing you to more efficiently use all of the space and all the drive letters on a multiple-disk system.

    Though it's only supported on dynamic disks

    The following operations can be performed only on dynamic disks:
    ...
    Extend a simple or spanned volume.