==== Dummy devices ====

While it's 
    # mkdev -l hdisk1 -p dummy -c disk -t hdisk -w 0000 

Note that running the command above may result in an error. However, if you run the following command afterwards, you will notice that the dummy disk device indeed has been created:

    # lsdev -Cc disk | grep hdisk1
    hdisk1 Defined    SSA Logical Disk Drive

On AIX 6.1 TL7 or AIX 7.1 TL1 you can easily rename a device
    # rendev -l hdisk3 -n hdisk300