Daily I/O on database

Hi, I'm trying to find daily I/O on the database and I ran the query below. Is the query correct ? It is scanning over petabytes of data everyday based on the output below. The database size is 2.5 TB and it is two node RAC. if the query is wrong could you please upload the right query to find daily I/O?

MUKUL  prod_dcop >r
  1  select trunc(sample_time) data_wise,function_name, round(sum(SMALL_READ_MEGABYTES)/(1024*1024)) small_TB_R,round(sum(SMALL_WRITE_MEGABYTES)/(1024*1024)) small_TB_W,
  2  round(sum(LARGE_READ_MEGABYTES)/(1024*1024)) large_TB_r,round(sum(LARGE_WRITE_MEGABYTES)/(1024*1024)) large_TB_w