Log buffer to tune

 Hi ,

In our database we are getting redo buffer allocation retries value very high,

SELECT R.VALUE "Retries",E.VALUE "Entries",R.VALUE/E.VALUE*100 "Percentage"
FROM V$SYSSTAT R,V$SYSSTAT E
WHERE R.NAME = 'redo buffer allocation retries'
AND E.NAME ='redo entries'; 

   Retries    Entries           Percentage
----------        ----------            ----------   
     12285  100971656   .012166781

Could you pls help me how to tune log buffer

log_buffer=14242816

Regards,

Jitender Kr. Lakra