If you do a major upgrade of Icinga 2 and use a database, please see
http://docs.icinga.org/icinga2/latest/doc/module/icinga2/chapter/upgrading-icinga-2
how to upgrade the database.

To rotate Icinga 2's logfiles, you can copy %%EXAMPLESDIR%%/newsyslog/icinga2
to %%LOCALBASE%%/etc/newsyslog.conf.d/