Granules:39
                                             BASEADDR            .DB_BLOCK_SIZE = 8192(大概就是一个buffer大小)
|==================|                         |--------|          .DB_CACHE_SIZE = 39*4=156M
|   Fixed  SGA     |                         |21000000|                   
|==================|                         |21400000|                    *.Buffer Cache includes 39 x 4M granules
|   Free Space     |                         |21800000|                    *.Each granule contains 500 buffers         --4*1024*1024/8192=512)  
|- - - - - - - - - |                         |21C00000|                    *.Buffer Cache contains 500*39  buffers     --39 granules
| . . . . . . .    |                         |22000000|
|==================|                         |22400000|              
|- - - - - -  -  - |                         |22800000|         
| . . . .  . . . . |--->Buffer Cache -->Addr |22C00000|             ------------------------------------
| Buffer Cache     |                         |23000000|             |Block Size   |  Buffers Per Granule|
|. . . . . . .  . .|                         |23400000|             |-------------|---------------------|
|- - - - - - - - - |                         |23800000|             |             |     4mb     16mb    |
|- - - - - - - - - |                         |....... |             |-------------|---------------------|
|==================|                         |28000000|             |2048         |     1875  |   7503  |
|   Java Pool      |                         |28400000|             |4096         |     979   |   3916  |
|==================|                         |28800000|             |8192         |     500   |   2002  |
|   Large Pool     |                         |28C00000|             |16384        |     253   |   1012  |
|==================|                         |29000000|             |32768        |     127   |   509   |
|- - - - - -  -  - |                         |29400000|             -------------------------------------
| . . . .  . . . . |                         |29800000|          备注:根据granule_size/block_size=buffer_num
| Shared Pool      |                         |29C00000|
|. . . . . . .  .  |                         |2A000000|
|==================|                         |2A400000|
| Redo Buffer      |                         ---------- 
|==================|                          

                         
3.Buffer Headers
*.Each buffer has a buffer header                                    --每个buffer都有个buffer header
*.In 9.2.0.4 buffer headers are 188 bytes                            --9204 buffer header 188 bytes
*.Buffer headers are stored in same granule as buffers               --buffer header和content都存储在相同的同一个granule
*.Buffer headers include                                             --buffer header主要包含: 
                            .Replacement list        -类似lru list     
                            .Hash list               -hash list                     
                            .Pointer to buffer       -指向具体buffer的指针                       

示例:
Buffer Cache Granule Chains

---------------------------------------------------------------------------------------------------------
| Header  | Header    |  Header   |   Header   |   Header   |     Header    |   Header    |   Header    |
|-------------------------------------------------------------------------------------------------------|
|         |           |           |            |            |               |             |------|------|<-buffers
|         |           |           |            |            |               |             |------|------|
|         |           |           |            |            |               |             |------|------|<-buffers
|         |           |           |            |            |               |             |------|------|
---------------------------------------------------------------------------------------------------------                                                             
 Granule1    Granule2     ..         ..            ..               ..            ...        granule N