oracle redo 4k优化：ssd 必做，性能可以提升10%

--sdd 盘调整redo大小为4K（原来是512byte）性能可以提升最少10%




select member  from v$logfile;
select group#,thread#,bytes/1024/1024,status   from v$log; 
ALTER SYSTEM SET "_DISK_SECTOR_SIZE_OVERRIDE"=TRUE scope=both sid='*';
 
alter database add logfile thread 1 group 11  '/oradata/orcl/redo11.log' size 500M blocksize 4096;
alter database add logfile thread 1 group 12  '/oradata/orcl/redo12.log' size 500M blocksize 4096;
alter database add logfile thread 1 group 13  '/oradata/orcl/redo13.log' size 500M blocksize 4096;
alter database add logfile thread 1 group 14  '/oradata/orcl/redo14.log' size 500M blocksize 4096;
 

--原来是512，现在变成了4k
[oracle@node1:/home/oracle]$ dbfsize /oradata/orcl/redo01.log

Database file: /oradata/orcl/redo01.log
Database file type: file system
Database file size: 245760 512 byte blocks
[oracle@node1:/home/oracle]$ dbfsize /oradata/orcl/redo11.log

Database file: /oradata/orcl/redo11.log
Database file type: file system
Database file size: 128000 4096 byte blocks
[oracle@node1:/home/oracle]$ 



--删除历史redo
alter database drop logfile group 1;
alter database drop logfile group 2;
alter database drop logfile group 3;