相关参考:
1、环境背景介绍
使用Oracle 11.2.0.4进行实验，项目是进行Active Data Guard搭建过程。由于环境条件所限，笔者实现在一台物理机上实现Primary和Standby。
SQL> select * from v$version;
BANNER
--------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - Production
PL/SQL Release 11.2.0.4.0 - Production
CORE 11.2.0.4.0 Production
TNS for Linux: Version 11.2.0.4.0 - Production
NLSRTL Version 11.2.0.4.0 - Production
2、/dev/shm过小引起故障
其他配置过程和官方推荐安装Active Dataguard方法相同。进行参数配置、密码文件创建、Oracle Net文件配置和Standby端参数文件创建后，使用RMAN进行duplicate过程，脚本如下：
run {
duplicat target database for standby from active database
spfile
parameter_value_convert 'ora11g','ora11gsy'
set db_unique_name='ora11gsy'
set log_archive_max_processes='5'
set fal_client='ora11gsy'
set fal_server='ora11g'
set standby_file_management='AUTO'
set log_archive_config='dg_config=(ora11g,ora11gsy)'
set log_archive_dest_2='service=ora11g async valid_for=(ONLINE_LOGFILE,PRIMARY_ROLE) db_unique_name=ora11g';
}
此时primary和standby实例都在启动状态，运行RMAN连接并执行脚本。
[oracle@SimpleLinux dbs]$ rman nocatalog
Recovery Manager: Release 11.2.0.4.0 - Production on Thu Apr 10 11:21:49 2014
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
RMAN> connect target sys/oracle@ora11g
connected to target database: ORA11G (DBID=4239941846)
using target database control file instead of recovery catalog
RMAN> connect auxiliary sys/oracle@ora11gsy
connected to auxiliary database: ORA11GSY (not mounted)
执行脚本：
RMAN> @cr_phy_standby
RMAN> run {
2> duplicate target database for standby from active database
3> spfile
4> parameter_value_convert 'ora11g','ora11gsy'
5> set db_unique_name='ora11gsy'
（篇幅原因，有省略……）
sql statement: alter system set log_archive_config = ''dg_config=(ora11g,ora11gsy)'' comment= '''' scope=spfile
sql statement: alter system set log_archive_dest_2 = ''service=ora11g async valid_for=(ONLINE_LOGFILE,PRIMARY_ROLE) db_unique_name=ora11g'' comment= '''' scope=spfile
Oracle instance shut down
connected to auxiliary database (not started)
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 04/10/2014 11:51:19
RMAN-05501: aborting duplication of target database
RMAN-03015: error occurred in stored script Memory Script
RMAN-04014: startup failed: ORA-00845: MEMORY_TARGET not supported on this system
duplicate过程报错，执行失败。
从分析看，应该是Oracle运行和内部共享内存分配有关。Linux中的/dev/shm对应tmpfs，也就是临时共享内存结构。当前大小为：
[root@SimpleLinux ~]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 48G 13G 33G 28% /
tmpfs 448M 160M 288M 36% /dev/shm
当前系统中包括两个实例对象，消耗的共享内存要超过一个实力的情况。所以需要调节增大这部分大小。
[root@SimpleLinux ~]# vi /etc/fstab
#
# /etc/fstab
# Created by anaconda on Wed Mar 12 08:33:33 2014
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=19248f54-250c-46a0-8e5d-ec26a6a08342 / ext4 defaults 1 1
UUID=5ce24d42-a713-4b6c-8d9b-0d780346e093 swap swap defaults 0 0
tmpf