ORA-00821: Specified value of sga_target 3072M is too small, needs to be at least 12896M

在测试PlateSpine克隆的数据库服务器时，由于资源有限，克隆过来的数据库服务器只给了9G的内存，结果在测试时，老是会出现OOMkiller导致宕机,即out of memory killer,是linux下面当内存耗尽时的的一种处理机制。当内存较少时，OOM会遍历整个进程链表，然后根据进程的内存使用情况以及它的oom score值最终找到得分较高的进程，然后发送kill信号将其杀掉。 于是调整了一下sga_target和sga_max_size这两个参数，结果重启的时候悲剧了:

[oracle@mylnx01 ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.5.0 - Production on Thu Dec 15 09:28:11 2016

Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.

Connected to an idle instance.

SQL> startup

ORA-00821: Specified value of sga_target 3072M is too small, needs to be at least 12896M

SQL> startup nomount

ORA-00093: _shared_pool_reserved_min_alloc must be between 4000 and 0

SQL>

出现这个这个错误，突然想起来这个服务器设置过shared_pool_size参数，于是生成pfile，检查initGSP.ora，如下所示，

SQL> create pfile='/u01/app/oracle/product/10.2.0/db_1/dbs/initGSP.ora' from spfile;

File created.

手工将.shared_pool_size设置为0， 然后启动数据库实例，问题解决。如下所示：

SQL> startup pfile='/u01/app/oracle/product/10.2.0/db_1/dbs/initGSP.ora'

ORACLE instance started.

Total System Global Area 3221225472 bytes

Fixed Size                  2099752 bytes

Variable Size             637535704 bytes

Database Buffers         2533359616 bytes

Redo Buffers               48230400 bytes

Database mounted.

Database opened.

SQL> exit