If you use default setting, then SMP3 write logs to database, it uses too much database space.
So I recommend to set "com.sap.mobile.platform.server.support.logging.disable_db_appender " to "true".
Please see the document.
Overriding Logging Settings
http://help.sap.com/saphelp_smp309svr/helpdata/en/d0/2d52ace799492ab982abfeb8c53dfc/content.htm
Thanks.
Tsuyoshi Yagi