Oracle DB - 修改資料庫參數 memory_max_target 重啟DB遭遇錯誤

修改資料庫參數 memory_max_target 之後重啟DB遭遇錯誤

1. ORA-00845: MEMORY_TARGET not supported on this system

SQL> ALTER SYSTEM SET memory_max_target = 1887436800 SCOPE=SPFILE;

System altered.

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL>

SQL> startup

ORA-00845: MEMORY_TARGET not supported on this system

[解決方式]

從alert log 可以看到類似的警告訊息。

WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 1996488704 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 1936601088 and used is 237568 bytes. Ensure that the mount point is /dev/shm for this directory.

memory_target needs larger /dev/shm

1. vi /etc/fstab

tmpfs                   /dev/shm                tmpfs   defaults,size=96g        0 0

2. reboot os

3. startup database

2. ORA-27102: out of memory

SQL> ALTER SYSTEM SET memory_max_target ='16G' SCOPE=SPFILE;

System altered.

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL>

SQL> startup

ORA-27102: out of memory

Linux-x86_64 Error: 12: Cannot allocate memory

Additional information: 26

Additional information: 327685

Additional information: 1711276032

[解決方式]
 memory_max_target 不可超過 實體記憶體 + Swap Space。

$ free
             total       used       free     shared    buffers     cached
Mem:       3782888    1674632    2108256     232144      34832     914080
-/+ buffers/cache:     725720    3057168
Swap:     10239996          0   10239996


1. 把  memory_max_target 調整到適合大小，再 startup database
2. 增加實體記憶體或swap space，，再 startup database

3. 其他注意事項

If AMM is enabled.

(Do not)勿調整SGA_MAX_SIZE

SGA_MAX_SIZE會自動調整成和MEMORY_MAX_TARGET相同值。

If AMM is disabled.

(Do not)勿調整SGA_MAX_SIZE超過 MEMORY_MAX_TARGET

SQL> startup
ORA-00843: Parameter not taking MEMORY_MAX_TARGET into account

ORA-00849: SGA_TARGET 12884901888 cannot be set to more than MEMORY_MAX_TARGET 2013265920.