1 /LOGICAL_IO
Specifies that the target GPT is to be accessed using Logical I/O operations. If neither /LOGICAL_IO nor /VIRTUAL_IO is specified, GPT access using Virtual I/O will be attempted first and followed by an attempt to use Logical I/O if [000000]GPT.SYS is not found. If the file [000000]GPT.SYS is correctly placed on the disk, the output of /LOGICAL_IO and /VIRTUAL_IO will be the same.
2 /VIRTUAL_IO
Specifies that the target GPT is to be accessed using Virtual I/O operations. If neither /LOGICAL_IO nor /VIRTUAL_IO is specified, GPT access using Virtual I/O will be attempted first and followed by an attempt to use Logical I/O if [000000]GPT.SYS is not found. If the file [000000]GPT.SYS is correctly placed on the disk, the output of /LOGICAL_IO and /VIRTUAL_IO will be the same.