ORA-27102及ORA-00845故障处理

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ORA-27102及ORA-00845故障处理

操作系统版本：Oracle Linux Server release 5.8
数据库版本：11.2.0.3.0
###1.ORA-270102故障处理
####1.1 故障现象

####1.2 故障原因
是因为操作参数没有设置为允许sga所指定大小的内存可以被锁定，操作系统参数max locked memory设置为unlimited

####1.3 检查操作系统参数并做修改
####1.3.1检查操作系统参数

oracle@devpddb $ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 63943
max locked memory       (kbytes, -l) unlimited
max memory size         (kbytes, -m) unlimited
open files                      (-n) 65536
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 32768
cpu time               (seconds, -t) unlimited
max user processes              (-u) 65536
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

####1.3.2修改操作系统参数
修改/etc/security/limits.conf加入以下信息

oracle		soft	memlock		65536
oracle		hard	memlock		65536

###2.ORA-00845故障处理
再次登录数据库出现ORA-00845

####2.1 检查/dev/shm设置
默认为物理内存的50%

该系统的物理内存为8GB，说明/dev/shm已经为物理内存

####2.2 检查数据库内存参数
方法一：登录数据库，使用show parameter检查

方法二：登录数据库，生成pfile进行查看

sqlplus / as sysdba
create pfile='/home/oracle/initpfile_12.2.ora' from spfile;

说明：由于此处数据库实例不可用，所以采用方法二查看

####2.3 调整数据库内存参数
#####2.3.1 减小memory_target

vi pfile20180713.ora
*db*.__db_cache_size=1828716544
*db*.__java_pool_size=16777216
*db*.__large_pool_size=16777216
*db*.__oracle_base='/u01/app/oracle'#ORACLE_BASE set from environment
*db*.__pga_aggregate_target=2030043136
*db*.__sga_target=3808428032
*db*.__shared_io_pool_size=0
*db*.__shared_pool_size=1895825408
*db*.__streams_pool_size=16777216
*.audit_file_dest='/u01/app/oracle/admin/***/adump'
*.audit_trail='db'
*.compatible='11.2.0.0.0'
*.control_files='/u01/app/oracle/oradata/***/control01.ctl','/u01/app/oracle/oradata/***/control02.ctl'
*.db_block_size=8192
*.db_domain=''
*.db_name='***'
*.diagnostic_dest='/u01/app/oracle'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=***XDB)'
*.memory_target=4294967296 #5829033984
*.nls_language='SIMPLIFIED CHINESE'
*.nls_territory='CHINA'
*.open_cursors=300
*.processes=3000
*.remote_login_passwordfile='EXCLUSIVE'
*.sessions=3305
*.undo_tablespace='UNDOTBS1'

报错如下：

startup pfile='/home/oracle/pfile20180713.ora';
ORA-27100: shared memory realm already exists
Linux-x86_64 Error: 17: File exists

#####2.3.2 再次调整参数
再次显式关库

shutdown abort

修改参数文件

vi pfile20180713.ora 
*db*.__db_cache_size=1828716544
*db*.__java_pool_size=16777216
*db*.__large_pool_size=16777216
*db*.__oracle_base='/u01/app/oracle'#ORACLE_BASE set from environment
*db*.__pga_aggregate_target=2030043136
*db*.__sga_target=2576980377 #3808428032
*db*.__shared_io_pool_size=0
*db*.__shared_pool_size=1895825408
*db*.__streams_pool_size=16777216
*.audit_file_dest='/u01/app/oracle/admin/***/adump'
*.audit_trail='db'
*.compatible='11.2.0.0.0'
*.control_files='/u01/app/oracle/oradata/***/control01.ctl','/u01/app/oracle/oradata/***/control02.ctl'
*.db_block_size=8192
*.db_domain=''
*.db_name='***'
*.diagnostic_dest='/u01/app/oracle'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=devpddbXDB)'
*.sga_max_size=524288000   #add
*.memory_target=4294967296 #5829033984
*.nls_language='SIMPLIFIED CHINESE'
*.nls_territory='CHINA'
*.open_cursors=300
*.processes=3000
*.remote_login_passwordfile='EXCLUSIVE'
*.sessions=3305
*.undo_tablespace='UNDOTBS1'

#####2.3.3 使用pfile启动数据库

startup pfile='/home/oracle/pfile20180713.ora';

问题解决，接下来重启数据库
#####2.3.4 重启数据库

create spfile from pfile='/home/oracle/pfile20180713.ora';
shutdown immediate
startup

###3.知识补充
####3.1SGA和PGA关系梳理

SGA_TARGET始终要 <= sga_max_size
####3.1.1memory_target=非0

• sga_target ≤ memory_target ≤ memory_max_target
• sga_max_size ≤ memory_target
• memory_target ≥ sga_target+pga_aggregate_target
  ####3.1.2memory_target=0
• sga_target < memory_max_target
• sga_target≤sga_max_size≤memory_target

####3.2memory_target相关

• memory_target为总内存的80%
• sga_max_size和__sga_target为memory_target的60%

####3.3内存有关的视图

 select * from v$sga_dynamic_components
 select * from v$sga_dynamic_free_memory
 select * from v$pgastat
 select * from v$sga
 select * from v$sgastat
 SELECT NAME, PHYSICAL_READS, DB_BLOCK_GETS, CONSISTENT_GETS,
       1 - (PHYSICAL_READS / (DB_BLOCK_GETS + CONSISTENT_GETS)) "Hit Ratio" FROM V$BUFFER_POOL_STATISTICS;

####3.4SGA参数值

SQL> select * from v$sga; 
NAME                VALUE 
----------             --------------------
Fixed Size                   454032 
Variable Size             109051904 
Database Buffers             385875968 
Redo Buffers                667648 

Fixed Size:
oracle 的不同平台和不同版本下可能不一样，但对于确定环境是一个固定的值，里面存储了 SGA 各部分组件的信息，可以看作引导建立 SGA 的区域。

Variable Size :
包含了 shared_pool_size、java_pool_size、large_pool_size 等内存设置

Database Buffers :
指数 据缓 冲区:
在 8i 中包 含 db_block_buffer×db_block_size、buffer_pool_keep、buffer_pool_recycle 三 部 分内 存 。
在 9i 中 包 含 db_cache_size 、db_keep_cache_size、db_recycle_cache_size、db_nk_cache_size。

Redo Buffers :
指日志缓冲区，log_buffer

####3.5ORACLE内存参数关系梳理

参考链接：
1.ORA-27102:out of memory Linux-x86_64 Error: 12: Cannot allocate memory的处理
2.实例启动时报ORA-00845的解决方法
3.Oracle基础知识–内存参数设置
4.oracle三对内存参数间关系之4sga_参数和memory_参数这两类上下级层次参数间的关系
5.ORACLE内存分配和调优总结