SYSAUX was introduced in 10g to store all auxiliary database metadata related to Oracle options and features. This is a mandatory tablespace and cannot be dropped. Therefore it is important to have all objects in this tablespace accessible at all times.
To find out what is stored in this tablespace, look at V$SYSAUX_OCCUPANTS:
SQL> select occupant_name, space_usage_kbytes from v$sysaux_occupants;
原文：http://blog.csdn.net/msdnchina/article/details/45193397