This parameter defines the group name with SYSADM authority for the database manager instance.
The SYSADM authority level is the highest level of administrative authority at the instance level. Users with SYSADM authority can run some utilities and issue some database and database manager commands within the instance.
If the value is not NULL, the SYSADM group can be any valid UNIX group name.
To restore the parameter to its default (NULL) value, use UPDATE DBM CFG USING SYSADM_GROUP NULL. You must specify the keyword NULL in uppercase.