we have a very old Oracle 220.127.116.11.0 database here that - unfortunately - is still used heavily as every day production system.
I want to start making plans on how to get this DB upgrade to a recent Oracle 12c.
Unfortunately, both DB versions don't seem to be able to talk to each other anymore (*). So to my current knowledge, the only solution is to import daily backups from 18.104.22.168.0 into 12c, which - from the technical point of view - works, but is not feasible because the 22.214.171.124.0 is used in daily business. Beside: The data on the 126.96.36.199.0 server is that large that an import of the backup in the 12c server (on a recent Dell server) takes about 6-8 hours.
So, the question is:
What might be a good approach for a upgrade strategy from 188.8.131.52.0 to 12c?
Thanks for any input.
(*) Of course old Oracle 184.108.40.206.0 clients can talk to the Oracle 220.127.116.11.0 server and recent 12c clients can talk to the 12c server. But there does not seem to be a client solution that can talk to both 18.104.22.168.0 and 12c.