一、内存管理第一层：
1、memory_target和memory_max_target开启自动内存管理。
rac1：
SQL> show parameter memory
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
hi_shared_memory_address integer 0
memory_max_target big integer 0
memory_target big integer 0
shared_memory_address integer 0
rac2：
SQL> show parameter memory
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
hi_shared_memory_address integer 0
memory_max_target big integer 0
memory_target big integer 0
shared_memory_address integer 0
二、内存管理第二层
1、sga_target、sga_max_size实现自动sga管理。
rac1：
SQL> show parameter sga
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 2928M
sga_target big integer 2928M
rac2：
SQL> show parameter sga
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 2928M
sga_target big integer 2928M
2、pga_aggregate_target实现自动pga管理。
rac1：
SQL> show parameter pga
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
pga_aggregate_target big integer 974M
rac2：
SQL> show parameter pga
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
pga_aggregate_target big integer 974M
三、内存管理第三层
rac1：
SQL> show parameter db_cache_size
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
db_cache_size big integer 0
SQL> show parameter log_buffer
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
log_buffer integer 16941056
SQL> show parameter shared_pool_size
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
shared_pool_size big integer 0
SQL> show parameter shared_pool_size
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
shared_pool_size big integer 0
SQL> show parameter large_pool
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
large_pool_size big integer 0
SQL> show parameter java_pool
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
java_pool_size big integer 0
SQL> show parameter stream
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
streams_pool_size big integer 0
rac2：
SQL> show parameter db_cache_size
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
db_cache_size big integer 0
SQL> show parameter log_buffer
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
log_buffer integer 16941056
SQL> show parameter shared_pool
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
shared_pool_reserved_size big integer 28521267
shared_pool_size big integer 0
SQL> show parameter large_pool
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
large_pool_size big integer 0
SQL> show parameter java_pool
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
java_pool_size big integer 0
SQL> show parameter streams
NAME TYPE VALUE
------------------------------------ --------------------------------- ------------------------------
streams_pool_size big integer 0
四、shm修改
如果想修改OS下oracle数据库内存大于OS内存一般以上，需要修改shm值（shm值默认为OS物理内存的50%），修改方法如下：
[[email protected] ~]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Fri Dec 4 19:49:21 2015
#
# 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=4225f161-f532-422f-82a4-1bc53ce8ea1a / ext4 defaults 1 1
UUID=07d3b54d-5537-4f84-bd9e-ceb3937312d0 swap swap defaults 0 0
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
[[email protected] ~]# vim /etc/fstab
#
# /etc/fstab
# Created by anaconda on Fri Dec 4 19:49:21 2015
#
# 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=4225f161-f532-422f-82a4-1bc53ce8ea1a / ext4 defaults 1 1
UUID=07d3b54d-5537-4f84-bd9e-ceb3937312d0 swap swap defaults 0 0
tmpfs /dev/shm,size=5g tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
重启服务器，或者杀掉占用shm内存的进程，重新挂在磁盘。