There is no need to clean out all 30 days the index data base
files nor the cachedir tags of mandb.  Those files are used
for whatis(1) as well as for apropos(1).

---
 systemd-210/tmpfiles.d/systemd.conf |    5 +++++
 1 file changed, 5 insertions(+)

--- systemd-210/tmpfiles.d/systemd.conf
+++ systemd-210/tmpfiles.d/systemd.conf	2014-06-11 13:47:59.470236564 +0000
@@ -14,6 +14,11 @@ f /var/log/wtmp 0664 root utmp -
 f /var/log/btmp 0600 root root -
 
 d /var/cache/man - - - 30d
+# mandb uses data base file which should not be cleared
+x /var/cache/man/index.*
+x /var/cache/man/CACHEDIR.TAG
+x /var/cache/man/*/index.*
+x /var/cache/man/*/CACHEDIR.TAG
 
 d /run/systemd/ask-password 0755 root root -
 d /run/systemd/seats 0755 root root -
