fail2ban up and including to 0.10.4 does not contain code to actually purge DB entries based on dbpurgeage.
Code for this has been introduced in 681bc2ef07ebdf749ccef624d8d598de42b0c6b6 in branch 0.11 but this has not seen a release yet. I am currently running the attached script on a daily basis to keep the database at a sane size. (It previously grew up to 2.5GB which put some load on the machine...) -- ceterum censeo microsoftem esse delendam.
fail2ban-cleanup
Description: Binary data
pgpsvdniGeYnM.pgp
Description: OpenPGP digital signature
