Having low data buffer hit ratio with AMM set

Good Morning everyone,

I am experiencing the SGA buffer hit ratio way below 90% yet the AMM has been set with the SGA_TARGET=0.  Why?  What am I missing?  I have increased the SGA and verified the SGA_Target is set to 0 and the memory management pieces are:

memory_max_target=9gb

memory_target = 9GB

Sga_max_size=9gb

Sga_target=0

I am still learning the Oracle11g and may have miss something in my investigation.  Any and all information is appreciated.

thanks,

243988