今天晚上新裝一臺Oracle 11g的數據庫,打算將SGA設大一點,知道 11g 中有一個新特新 MEMORY_TARGET,於是嘗一下鮮,誰知報了個 ORA-00845,報錯比較容易迷惑人,不借助Google真得想半天:
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SQL> alter system set memory_max_target=3G scope=spfile ; System altered. 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 |
來自Oracle的官方解析是:
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.
簡單來說就是 MEMORY_MAX_TARGET 的設置不能超過 /dev/shm 的大小:
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[oracle@FWDB FWDB]$ df -h | grep shm tmpfs 2.0G 0 2.0G 0% /dev/shm |
還真是撞到這個槍口上了:
馬上把它加大:
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[root@FWDB ~] # cat /etc/fstab | grep tmpfs tmpfs /dev/shm tmpfs defaults,size=4G 0 0 |
現在可以通過重啓使這個配置生效,也可以通過重新掛載來修改其大小:
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[root@FWDB ~] # mount -o remount,size=4G /dev/shm [root@FWDB ~] # df -h | grep shm tmpfs 4.0G 0 4.0G 0% /dev/shm |
再次啓動數據庫,沒有報錯了。