I wish to transition from Mainframe to Open Systems Storage Administration. How much training would I need in order to meet requirements for an AIX Administrator position?

Not very many…
AIX is very well structured system with EASY to manage resources. SSA in very well organized and very nicely documented. It organized in volume groups-logical volumes-physical volumes and with set of commands to set, format, defrag and replicate on each level. The AIX documentation is PLEASURE to read and use. There’s program called smitty and it has counterpart for a graphic terminal that handles most of jobs for you in a proper order. There’s option in the menu of smitty that will show you the command every time before execution so you can learn the commands from the smitty itself. If you need general UNIX training get “UNIX Essentials and UNIX Core” DVD the AIX docs are available online on their site. TO manage SSA it will take you two hours of reading and two hours of trying. Good luck.

Thanks AMRO1........I see that there is a UNIX for Beginners DVD as well. Is it necessary to take this DVD, or could I do with just the UNIX Essentials and UNIX Core DVD?

I think "Beginner" is kind of shortened version of the whole thing and as I'm reading it comes with no certs. Can't tell. We have the "Essentials and Core" as a standard training for new users (we have corp license).
Generally speaking SSA is very nicely documented and EASY to use:
there are "volume groups" which contain "logical volumes" which contain "physical volumes". Type lsvg in Google and it will come back with IBM's docs for all the stuff you need for SSA browse and read.