ORA-00845: MEMORY_TARGET not supported on this system-优快云博客

本文介绍了解决Oracle数据库启动时遇到的ORA-00845错误的方法。该错误通常由于共享内存设置不当导致。文章提供了两种调整共享内存大小的方式：通过修改配置文件或重新挂载。完成调整后，数据库可以正常启动。

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   SQL> alter system set memory_target=2G scope=spfile ;      
 

   System altered. 
 

   SQL> 
 

   SQL> shutdown immediate 
 

   Database closed. 
 

   Database dismounted. 
 

   ORACLE instance shut down. 
 

   SQL> startup ; 
 

   ORA-00845: MEMORY_TARGET not supported on this system 
 

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
简单来说就是 MEMORY_MAX_TARGET 的设置不能超过 /dev/shm 的大小

 
  查看/dev/shm 
  
 [oracle@FWDB FWDB]$ df -h | grep shm

   tmpfs                 2.0G     0  2.0G   0% /dev/shm 
  
 调整/dev/shm大小 
  
 方法一：修改配置文件 
  
    [root@FWDB ~]# cat /etc/fstab | grep tmpfs 
  
    tmpfs                   /dev/shm                tmpfs   defaults,size=4G 0 0 
  
 重启生效 
  
 方法二：重新挂载

mount -o remount,size=4G /dev/shm
[root@FWDB ~]# df -h | grep shm
tmpfs 4.0G 0 4.0G 0% /dev/shm
再次重启数据库，恢复正常。

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