I have bad news for you: by importing the disk into the another VG you ruined the boot sector - the boot code for AIX 6.1 is now overwritten by the boot code of AIX 5.3, which is different. The only way to restore it is to have a running 6.1 system which could write the boot sector over the disk. (To put it in a slang you might be more familiar with: its like issuing a "fdisk /mbr" on the disk.)

Once you get your machine running again, "dd" is not the tool to do backups at all in AIX. There is a tool called "mksysb" which completely backs up all the system area into a bootable image. Use a tape device as destination and you have a perfectly bootable (and restorable) system image on tape. You can also use a file (even on the originating system) as destination, bot you will need an external boot device (such as a CD, another tape, etc.) to boot from that and only then use the file to restore the system.

You might also want to read about the Logical Volume Manager (LVM) of AIX. It is the oldest and most mature one in the industry and most of the other UNIX suppliers have either copied its concepts (Linux LVMs) or outright licensed it (like HP for example). You should never use the rootvg (the default volume group of any AIX system) for non-system data, for instance - and after reading up on the concepts behind LVM you will know why.

There is a very good systems administration tool, called "SMIT". Start it by issuing "smit" (better yet: "smitty", to start it in non-graphic mode) and you can do most of the systems administration tasks. SMIT uses standard system commands and you can even look at how its doing it by pressing "PF6" in one of the final screens. Up comes a window with the command SMIT would issue. This way you can learn a lot about how things are done in AIX.

I hope this helps.

bakunin