db_writer_processes默认大小
db_writer_processes是DBWn进程数量的参数，默认=CPU_COUNT/8.
下面在我笔记本上看到的这个参数是=1，一个双核CPU-7250：
C:/Users/Administrator>systeminfo
......
......
系统制造商: Dell Inc.
系统型号: Vostro 1400
系统类型: X86-based PC
处理器: 安装了 1 个处理器。
[01]: x64 Family 6 Model 15 Stepping 13 GenuineIntel ~2001 Mhz
......
......
看到对应的db_writer_processes=1.
C:/Users/Administrator>sqlplus /nolog
SQL*Plus: Release 10.2.0.1.0 - Production on 星期二 1月 18 15:15:37 2011
Copyright (c) 1982, 2005, Oracle. All rights reserved.
idle> conn /as sysdba
已连接。
sys@TEST> show parameter db_writer;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_writer_processes integer 1
下面看到的是另一个环境的参数=2，由于是16核的CPU，所以16/8=2.
[oracle@crmdb2 ~]$ cat /proc/cpuinfo | grep name
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
model name : Intel(R) Xeon(R) CPU E7330 @ 2.40GHz
[oracle@crmdb2 ~]$ sqlplus /nolog
SQL*Plus: Release 10.2.0.3.0 - Production on Tue Jan 18 15:14:05 2011
Copyright (c) 1982, 2006, Oracle. All Rights Reserved.
SQL> conn /as sysdba
Connected.
SQL> show parameter db_writer;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_writer_processes integer 2
SQL>
-The End-