You mention dbmopen in your question. If you think DBI is old, well, dbmopen is older, and in contrast to DBI, it is in fact outdated. I remember when that was the primary option for persisting data to disk so it could be used beyond the lifetime of the Perl process. Nowadays, you can achieve the same effect by tieing a hash to an appropriate class. But despite this possibility, I would still go to DBI and DBD::SQLite for simple, file-system based storage. It's simple, it works well, and is easy to adapt to the common RDBMS products that are out there.
I just want to reinforce that the previous posts pointing you to DBI do indeed, in my opinion, set you on the right (write?) track to doing storage from Perl.