修改db_files參數，是否影響業務？

1、環境描述：
Oracle 10g RAC ,在線修改db_files參數

2、操作如下

SQL> show parameter db_files

NAME                     TYPE    VALUE
------------------------------------ ----------- ------------------------------
db_files                 integer     200

SQL> alter system set db_files=1000 scope=spfile sid='*';

System altered.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  536870912 bytes
Fixed Size          1268508 bytes
Variable Size         150996196 bytes
Database Buffers      381681664 bytes
Redo Buffers            2924544 bytes
ORA-01105: mount is incompatible with mounts by other instances
ORA-01174: DB_FILES is 1000 buts needs to be 200 to be compatible

--報錯，提示數據庫Mount與另一個實例mount不一致，修改后的參數為1000與另一個節點的參數200不一致。

3、解決方法
關閉第二個節點的實例，這樣就是同時關閉了兩個節點的實例，或者說需要關閉所有節點的實例。必然影響業務了。有的參數可以在線更改，有的參數可以滾動修改，這些都不影響業務。但是db_files 這個參數必然影響業務了，只能找一個對業務影響最小的時間點重啟所有實例即可。

SQL> conn / as sysdba
Connected.
SQL> startup
ORA-01081: cannot start already-running ORACLE - shut it down first
SQL> shutdown abort;
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  536870912 bytes
Fixed Size          1268508 bytes
Variable Size         150996196 bytes
Database Buffers      381681664 bytes
Redo Buffers            2924544 bytes
Database mounted.
Database opened.
SQL>