LTO 6 should be able to handle migrating from LTO 4. It's an x-2 thing...
Theoretically you could start out at 7.2 on your P9. Complete your
upgrade and then upgrade it to 7.3. That would be the cleanest.
Failing that there is a documented process at the Knowledge Center called
a Data Migration. This is how you upgrade from hardware which doesn't
support the release available on the target:
https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_73/rzamc/rzamc1.htm
Now, there are always those who think they're still running an AS/400 or
some such thing. They figure all they need to do is restore their program
and file libraries on to the target system and they'll be just fine. Done
wrong you'll be cleaning up stuff that was forgotten for months. Fixing
security issues, etc. Happens a lot though...
Some people really clobber it by restoring IBM i objects on to the target
system and can really screw stuff up. Kind of like just restoring your
BPCS 405CD data files on to a system running ERPLX 8.3.03 and expecting it
to work. The files just don't match the application.
Rob Berendt
midrange.com
