ORA-00845: MEMORY_TARGET not supported on this system

最新推荐文章于 2021-04-18 17:07:58 发布

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最新推荐文章于 2021-04-18 17:07:58 发布

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本文介绍了解决Oracle数据库启动时遇到的ORA-00845错误的方法，该错误通常与系统共享内存设置不足有关。文章提供了两种调整共享内存大小的方式：一是通过修改/etc/fstab文件并重新挂载/dev/shm；二是直接使用mount命令临时调整大小。

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SQL> startup nomount;
ORA-00845: MEMORY_TARGET not supported on this system
SQL>

alert_log:
Wed Mar 13 10:38:04 2013
Adjusting the default value of parameter parallel_max_servers
from 160 to 135 due to the value of parameter processes (150)
Starting ORACLE instance (normal)
WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 1610612736 bytes. /dev/shm is either not mounted or is mounted with available space less than this size. Please fix this so that MEMORY_TARGET can work as expected. Current available is 773545984 and used is 242552832 bytes. Ensure that the mount point is /dev/shm for this directory.
memory_target needs larger /dev/shm

Oracle的官方解析：
Starting with Oracle Database 11g, the Automatic Memory Management feature requires more shared memory (/dev/shm)and file descriptors. The size of the shared memory should be at least the greater of MEMORY_MAX_TARGET and MEMORY_TARGET for each Oracle instance on the computer. If MEMORY_MAX_TARGET or MEMORY_TARGET is set to a non zero value, and an incorrect size is assigned to the shared memory, it will result in an ORA-00845 error at startup.

[root@pc02 ~]# df -h | grep shm
tmpfs 970M 232M 738M 24% /dev/shm
[root@pc02 ~]# cat /etc/fstab | grep tmpfs
tmpfs /dev/shm tmpfs defaults 0 0
[root@pc02 ~]#

通过重新挂载来修改其大小：
一：
[root@db2 ~]#vi /etc/fstab //更换/dev/shm默认大小为2G

LABEL=/                 /                       ext3    defaults        1 1
LABEL=/boot             /boot                   ext3    defaults        1 2
#tmpfs                   /dev/shm               tmpfs   defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults,size=2048M 0 0
devpts                  /dev/pts                devpts gid=5,mode=620 0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
LABEL=SWAP-hda3         swap                    swap    defaults        0 0

注：本行defaults,size=10240M 中间无空格
[root@db2 ~]#
[root@db2 ~]# umount /dev/shm
[root@db2 ~]# mount /dev/shm
[root@pc02 ~]# df -h
Filesystem            Size Used Avail Use% Mounted on
/dev/sda1             428G   59G 348G 15% /
/dev/sda2              16G 177M   15G   2% /tmp
tmpfs                 4.0G 232M 3.8G   6% /dev/shm
[root@pc02 ~]#

二：
[root@pc02 ~]# mount -o remount,size=4G /dev/shm
[root@pc02 ~]# df -h | grep shm
tmpfs                 4.0G 232M 3.8G   6% /dev/shm
[root@pc02 ~]#
[root@pc02 ~]# cat /etc/fstab
LABEL=/                 /                       ext3    defaults        1 1
LABEL=/tmp              /tmp                    ext3    defaults        1 2
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
LABEL=SWAP-sda3         swap                    swap    defaults        0 0
[root@pc02 ~]#

SQL> startup
ORACLE instance started.

Total System Global Area 1603411968 bytes
Fixed Size                  2228784 bytes
Variable Size             905973200 bytes
Database Buffers          687865856 bytes
Redo Buffers                7344128 bytes
Database mounted.
Database opened.
SQL>