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Wednesday, January 10, 2018

How to find Exadata cell flash cache hits

Below are the Commands to find the cell_flash_cache hits:

SQL> select owner,cell_flash_cache from dba_segments where segment_name='<segment name>';

SQL> select name,value from v$mystat natural join v$statname where name in ('physical read total IO requests','cell flash cache read hits');

SQL>select * from u1.t1 where rownum<3;

SQL> select name,value from v$mystat natural join v$statname where name in ('physical read total IO requests','cell flash cache read hits');

Output of above commands will display the values of physical read total IO requests & cell flash cache read hits. check weather both the value is increasing???For first selection there is physical read which is obvious but from 2nd time onwords the selection should happen from flash cache.

Now will check if the values are not increaseing

SQL> select * from u1.t1 where rownum<4;
SQL>select name,value from v$mystat natural join v$statname where name in ('physical read total IO requests','cell flash cache read hits');

SQL> select * from u1.t1 where rownum<10;

SQL>select name,value from v$mystat natural join v$statname where name in ('physical read total IO requests','cell flash cache read hits');

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