Ask about Tuning db buffer cache in oracle 9.2.0.4 64 bit on Unix

   Hi all,

    I have been read about tuning database buffer cache. There are some question that I need to help:

    I used bellow script to select data from v$db_cache_advice

select

   size_for_estimate         c1 ,

   buffers_for_estimate      c2 ,

   estd_physical_read_factor  c3,

   estd_physical_reads        c4

from

   v$db_cache_advice

where

   name = 'DEFAULT'

and

   block_size  = (SELECT value FROM V$PARAMETER

                   WHERE name = 'db_block_size')

and

   advice_status = 'ON';

   Result is:

c1             c2            c3           c4

-------       --------     ---------    ----------------

512          60872 11.3453 23946721811

1024 121744 8.6482 18253952878

1536 182616 5.9248 12505615251

2048 243488 4.0334 8513420565

2560 304360 2.6868 5670996016

3072 365232 1.8299 3862311020

3584 426104 1.3412 2830869873

4096 486976 1.2011 2535133313

4608 547848 1.0932 2307338577

5120 608720 1.0083 2128157499

5184 616329 1 2110713560

5632 669592 0.9422 1988623653

6144 730464 0.8914 1881482944

6656 791336 0.8518 1797852523

7168 852208 0.8208 1732441662

7680 913080 0.8039 1696847587

8192 973952 0.7894 1666101701

8704 1034824 0.7763 1638488458

9216 1095696 0.7637 1612044060

9728 1156568 0.7514 1585963796

10240 1217440 0.7392 1560325359

   Belong document, current size of db buffer cache is :   5120 MB ? Am I right ? And I need determine cache hit ratio , I'm going to use :