In order to perform any type of migration activity on an image mode virtual disk (VDisk), the image mode VDisk must first be converted into a managed mode disk. This happens automatically whenever any kind of migration activity is attempted. Once this image to managed migration operation has occurred, the VDisk becomes a managed mode VDisk and is treated the same way as any other managed mode VDisk.
If the image mode disk has a partial last extent, then this last extent in the image mode VDisk must be the first to be migrated. This migration is handled as a special case. Once this special migration operation has occurred, the VDisk becomes a managed mode VDisk and is treated in the same way as any other managed mode VDisk. If the image mode disk does not have a partial last extent, no special processing is performed. The image mode VDisk is simply changed into a managed mode VDisk and is treated in the same way as any other managed mode VDisk.
An image mode disk can also be migrated to another image mode disk. It becomes managed while the migration is ongoing, but returns to image mode when the migration is complete.