Which disk image support siplit into files, VDI, VMDK, or VHD?

Question

Different from this quesiton, What disk image should I use with VirtualBox, VDI, VMDK, VHD or HDD?

1. Does only vmdk format support 'splitting the storage file into files'? What about other formats?
2. For supporting format, is its specification or implementation Open Source?

Thanks.

Answer 1

As of now, only VMDK supports splitting. It is proprietary.

There is a limited workaround: With Microsoft Windows and Linux versions that do support spanned volumes, you can create multiple virtual hard disks and have the operating system span a logical volume across them.

The limitation of this workaround is lies in the operating system's limitation of the number of hard disks that a logical volume can span.