Apache mod_balacer

Hi,

I want use apache mod_balacer to use 2 Tomcats like Master-Slave. All
request are redirect to Tomcat 1 (Master) if Master is down, every
request will be redirect to Tomcat 2(slave).


I can config Apache mod_balacer like Master-Master, but i can't Master-
Slave, how can do it?

Thanks.