Virtual Input Output (VIO) Server is a vital concept and component in PowerVM virtualization. It’s the “core” server that virtualizes your physical device and assign them to the client LPAR . There’s alot of concepts and best practices in this area (VIO & SAN). I am still quite new to the IBM PowerVM virtualization concepts so I have been reading up quite a bit.
These are 2 very decent documents that I have been reading. Of course, the IBM PowerVM Virtualization redbook is pretty good too!