creating password file

http://satya-dba.blogspot.in/2009/08/rollback-segments-in-oracle.html

http://docs.oracle.com/cd/B28359_01/server.111/b28310/dba007.htm#ADMIN11061

http://newgendba.blogspot.in/2009/03/connect-to-oracle-as-sys-via-toad-or.html