2016-05-26 05:07 AM
2016-05-27 07:28 AM
on 7-mode, "man na_syslogd" says, that there is a once per week rotation, so I guess, there's not much you can do regarding log rotation.
What I did was I built a syslog (syslog-ng) server that collects everything off the filer, so I can archive and analyze filer logs as I need it.
Maybe this is an option for you.