[SR-Users] Understanding some usrloc modparams

Hello, I have an installation using usrloc + db_mode=1. If I want on db_mode=1 or db_mode=2 the expired contacts to be cleaned up I have to enable the modparam db_timer_clean: https://www.kamailio.org/docs/modules/devel/modules/usrloc.html#usrloc.p.db… The docs say: "*Enable (1) or disable (0) cleaning of expired db records on timer basis for db_mode WRITE-BACK and WRITE-THROUGH. It uses the secondary timer process.*" I have the following doubts: 1- What does the reference "it uses *the* secondary timer process" mean? Is there a specific secondary timer just for this purpose? 2- Is #1 related to the modparam timer_procs? (so it uses one of those when enabled?) 3- Why/When would you need a timer_proces modparam with a value higher than "1"? Thanks, Joel.