TAXC60GET官方解释.,10g      PGA自动管理

 

  1. 测验蒙受
    OS: RHEL5U5(32bit)
    DB: Oracle 11.2.0.3.0(32bit)

  2.   格外原因. 
    2.1 oracle 11g默认sga_target为0,如下图, Oracle
    10g开始,引入SGA_TAENCOREGET伊始化参数, 让oracle自动管理SGA中(Buffer cache
    (DB_CACHE_SIZE),Shared pool (SHARED_POOL_SIZE),Large pool
    (LARGE_POOL_SIZE),Java pool (JAVA_POOL_SIZE),Streams pool
    (STREAMS_POOL_SIZE))的内部存款和储蓄器自动分配,即ASSM(Automatic Shared Memory
    Management). 如下为引自oracle官方文书档案解释.如下.

概念相比介绍

SYS> show parameter sga;

 

NAME                                 TYPE           VALUE

信任有些人会对ORACLE当中的AMM(Automatic
Memory Management)与ASMM(Automatic Shared Memory
Management)有些吸引或歪曲,不清楚两个的纠纷,本文子禽从多少个地方来计算一下两端的异同。如有不足或疏漏之处,敬请指正!


 


从ORACLE发表的版本历史(时间轴)来看,ORACLE的内部存款和储蓄器管理的差不离历程如下:

lock_sga                             boolean        FALSE
pre_page_sga                     boolean       FALSE
sga_max_size                      big integer   632M
sga_target                           big integer    0
SYS> 

 

SGA_TA景逸SUVGET官方解释.

ORACLE  9i 
    
PGA自动处理,SGA手动管理

SGA_TARGET

Property Description
Parameter type Big integer
Syntax SGA_TARGET = integer [K | M | G]
Default value 0 (SGA autotuning is disabled for DEFERRED mode autotuning requests, but allowed for IMMEDIATE mode autotuning requests)
Modifiable ALTER SYSTEM
Range of values 64 MB to operating system-dependent
Basic Yes

SGA_TARGET specifies the total size of all SGA components.
If SGA_TARGET is specified, then the following memory pools are
automatically sized:

  • Buffer cache (DB_CACHE_SIZE)

  • Shared pool (SHARED_POOL_SIZE)

  • Large pool (LARGE_POOL_SIZE)

  • Java pool (JAVA_POOL_SIZE)

  • Streams pool (STREAMS_POOL_SIZE)

If these automatically tuned memory pools are set to nonzero values,
then those values are used as minimum levels by Automatic Shared Memory
Management. You would set minimum values if an application component
needs a minimum amount of memory to function properly.

The following pools are manually sized components and are not affected
by Automatic Shared Memory Management:

  • Log buffer

  • Other buffer caches, such as KEEP, RECYCLE, and other block sizes

  • Fixed SGA and other internal allocations

2.2 给SGA_TARGET设置与SGA_MAX_SIZE(632M)相册的值,张开ASSM成效.
SYS> alter system set sga_target=632M SCOPE=SPFILE;
System altered.

3 重启DB
3.1  SYS> startup force
ORA-00838: Specified value of MEMORY_TARGET is too small, needs to be
at least 644M
SYS> show parameter pga;
ORA-01034: ORACLE not available
Process ID: 0
Session ID: 54 Serial number: 5

3.2 依据如上报错音讯.能够看出SGA设置大了. 导致PGA小了,
故报错. MEMO汉兰达Y_TAENCOREGET=PGA+SGA.   SGA的最少值为10M,最大值为 4096 GB – 1,
见官方文档.

ORACLE
10g      PGA自动管理,SGA自动管理(ASMM,自动分享内部存储器管理)

PGA_AGGREGATE_TARGET

Property Description
Parameter type Big integer
Syntax PGA_AGGREGATE_TARGET = integer [K | M | G]
Default value 10 MB or 20% of the size of the SGA, whichever is greater
Modifiable ALTER SYSTEM
Range of values Minimum: 10 MB

Maximum: 4096 GB – 1

Basic Yes

PGA_AGGREGATE_TARGET specifies the target aggregate PGA memory
available to all server processes attached to the instance.

3.3 查看ORA-00838 报错, ORACLE解释.

jietestdb<*test11g*/u01/product/oracle/dbs>$oerr ora 00838
00838, 00000, “Specified value of MEMORY_TARGET is too small, needs to
be at least %sM”
// *Cause: The specified value of MEMORY_TARGET was less than the sum
of the 
//         specified values for SGA_TARGET and
PGA_AGGREGATE_TARGET.
// *Action: Set MEMORY_TARGET to at least the recommended value.

由上ORA-00838,ORACLE解释能够见见, 降低SGA值,或附加MEMOTiguanY_TATiguanGET值,
或还原修改前意况就可以减轻难点.
3.1 第一种减轻措施:
还原先前情状,不做SGA_TARGET或MEMORY_TARGET值改变.
     3.1.1 此DB已经被shutdown了, 直接startup DB不能够运维, 如下报错.
SYS> startup
ORA-00838: Specified value of MEMORY_TARGET is too small, needs to be
at least 644M
      3.1.2 因DB在闭馆状态下,也能够由spfile成立pfile,或由pfile
成立spfile. 此时我们测量检验DB
spfiletest11g.ora中,已经包蕴sga_target值,如下图. 

jietestdb<*test11g*/u01/product/oracle/dbs>$
jietestdb<*test11g*/u01/product/oracle/dbs>$strings
spfiletest11g.ora 
test11g.__db_cache_size=155189248
test11g.__java_pool_size=4194304
test11g.__large_pool_size=4194304
test11g.__oracle_base=’/u01/product’#ORACLE_BASE set from
environment
test11g.__pga_aggregate_target=230686720
test11g.__sga_target=432013312
test11g.__shared_io_pool_size=0
test11g.__shared_pool_size=251658240
test11g.__streams_pool_size=8388608
*.audit_file_dest=’/u01/product/admin/test11g/adump’
*.audit_trail=’db’
*.compatible=’11.2.0.0.0′
*.control_files=’/u01/product/oradata/test
11g/control01.ctl’,’/u01/product/oradata/test11g/control02.ctl’,’/data/test11g/control03.ctl’
*.db_block_size=8192
*.db_domain=”
*.db_name=’test11g’
*.db_recovery_file_dest=’/u01/product/fast_recovery_area’
*.db_recovery_file_dest_size=5218762752
*.diagnostic_dest=’/u01/product’
*.dispatchers='(PROTOCOL=TCP) (SERVICE=test11gXDB)’
*.fast_start_mttr_target=0
*.local_listener=’LISTENER_TEST11G’
*.log_archive_dest_1=’LOCATION=/data/test11g/arch/’
*.log_archive_format=’%t_%s_%r.arc’
*.memory_target=661651456
*.open_cursors=1000
*.processes=1000
*.remote_login_passwordfile=’EXCLUSIVE’
*.sec_case_sensitive_logon=FALSE
*.sessions=1105
*.sga_target=662700032
*.undo_tablespace=’UNDOTBS1′

     3.1.3 此时由 SPFILETEST11G.ORA创建INITTEST11G.ORA
SYS> create pfile from
spfile;

File created.
     3.1.4
VIM修改创设的inittest11g.ora文件,删除*.sga_target=662捌仟32的值
(因为spfiletest11g.ora为二进制文件,不能够用VI/VIM命令直接修改),
 重新创造spfiletest11g.ora,此时spfiletest11g.ora中就不会蕴藏sga_target的值.
SYS> create spfile from
pfile
;
File created.
    3.1.5 启动DB OK
SYS> startup
ORACLE instance started.
Total System Global Area  661209088 bytes
Fixed Size                  1346980 bytes
Variable Size             499122780 bytes
Database Buffers          155189248 bytes
Redo Buffers                5550080 bytes
Database mounted.
Database opened.
  
3.2 第三种办法,由如上形式创设出来的inittest11.ora PFILE开首化文档中,
间接助长*.sga_target=X (X为二个数值,
前提包证SGA的X值,被MEMOLacrosseY_TA奥迪Q3GET的值632M,减去剩余PGA的值大于10M(PGA最小值)),由修改后的PFILE创立SPFILE,
直接开发银行DB就可以.
3.3 第三种办法,与第三种艺术类似, 假使不想修改SGA_TA宝马X3GET的值,
能够在pfile初阶化文书档案中,
修改增大 *.memory_target=Y(Y为二个数值,Y值不可能超过物理内部存款和储蓄器大小)的值.
在由修改后的PFILE,制造SPFILE运转DB.

  1. 小结.
    4.1 如若是正式库PGA不要安装太小,要基于业务须要,
    假设用户进度有大的出现,排序等必要把PGA设置大点.
    平常PGA暗中认可值为六成的MEMOEvoqueY_TARGET值, SGA为80%的MEMORY_TARGET值.
    4.2 pfile与spfile如上文设置的新值,
    sga_target或memory_target在DB运维后,都会覆盖先前DB设置的sga_target或memory_target的值.

 

http://blog.itpub.net/28569596/viewspace-1172469/

 

ORACLE
11g      PGA,SGA统一机动管理(AMM,自动内部存款和储蓄器管理)

ORACLE
12c      跟11g一致,未有变化

 

 

法定文书档案的介绍资料如下:

 

·        
Oracle
9i

 

·        
Beginning
with Oracle9i, the dynamic SGA infrastructure allowed for the sizing of
the Buffer Cache, Shared Pool and the Large Pool without having to shut
down the database. Key features being:

o   Dynamic
Memory resizing

o   DB_CACHE_SIZE
instead of DB_BLOCK_BUFFERS

o   DB_nK_CACHE_SIZE
for multiple block sizes

o   PGA_AGGREGATE_TARGET
Introduction of Automatic PGA Memory management

 

·        
Oracle
Database 10g

 

·        
Automatic
Shared Memory Management (ASMM) was introduced in 10g. You enable the
automatic shared memory management feature by setting the SGA_TARGET
parameter to a non-zero value.

 

·        
Oracle
Database 11g

 

·        
Automatic
Memory Management is being introduced in 11g. This enables automatic
tuning of PGA and SGA with use of two new parameters named
MEMORY_MAX_TARGET and MEMORY_TARGET

·        
Oracle
Database 12c

           
Automatic Memory Management keeps the same behaviour as in 11g.

 

 

电动分享内部存款和储蓄器管理(Automatic
Shared Memory Management ASMM)是ORACLE
10g启幕引进的的新本事,ASMM用来贯彻SGA的全自动管理。。当启用自动分享内部存款和储蓄器管理后,不再需求为每一个内部存储器组件设定值,当然假如你设置SGA_TARGET的同时,设置了db_cache_size、shared_pool_size这么些参数,那么db_cache_size、shared_pool_size这几个参数值会作为最小值须要。官方关于Automatic
Shared Memory Management的介绍如下:

 

Automatic
Shared Memory Management

 

In
previous database releases, a database administrator (DBA) was required
to manually specify different SGA component sizes by setting a number of
initialization parameters, including the SHARED_POOL_SIZE,
DB_CACHE_SIZE, JAVA_POOL_SIZE, and LARGE_POOL_SIZE parameters.
Oracle Database 10g includes the Automatic Shared Memory Management
feature which simplifies the SGA memory management significantly. In
Oracle Database 10g, a DBA can simply specify the total amount of SGA
memory available to an instance using the SGA_TARGET initialization
parameter and the Oracle Database will automatically distribute this
memory among various subcomponents to ensure most effective memory
utilization.

 

When
automatic SGA memory management is enabled, the sizes of the different
SGA components are flexible and can adapt to the needs of a workload
without requiring any additional configuration. The database
automatically distributes the available memory among the various
components as required, allowing the system to maximize the use of all
available SGA memory.

 

ORACLE
10G版本开头生产了ASMM,自动SGA管理,它的面世一定程度上支持DBA化解了保管SGA的主题素材,通过安装参数SGA_TARGET来控制ASMM,其中SGA_TA昂CoraGET为零象征禁止使用ASMM,非零值表示启用ASMM。可是在10G
哈弗1等后期版本,ASMM还远远不够成熟,并且存在比较多的BUG,导致了相当多的难题。在ORACLE
10g Odyssey2后续版本中,ASMM才稳步完善并成熟。

 

到了11g从此,ORACLE又达成了PGA和SGA的联合机动管理,这些名称为自动化内存管理(Automatic Memory
Management,AMM)。从那一个演化进度来看,ORACLE从最初始的手动配置各种零部件参数,慢慢逐步向智能化、傻瓜化、自动化的侧向稳步前进。那一个是八个料定的野史趋势。关于AMM的合爱尔兰语档介绍如下:

 

About
Automatic Memory Management

 

The
simplest way to manage instance memory is to allow the Oracle Database
instance to automatically manage and tune it for you. To do so (on most
platforms), you set only a target memory size initialization parameter
(MEMORY_TARGET) and optionally a maximum memory size initialization
parameter (MEMORY_MAX_TARGET). The instance then tunes to the target
memory size, redistributing memory as needed between the system global
area (SGA) and the instance program global area (instance PGA). Because
the target memory initialization parameter is dynamic, you can change
the target memory size at any time without restarting the database. The
maximum memory size serves as an upper limit so that you cannot
accidentally set the target memory size too high, and so that enough
memory is set aside for the Oracle Database instance in case you do want
to increase total instance memory in the future. Because certain SGA
components either cannot easily shrink or must remain at a minimum size,
the instance also prevents you from setting the target memory size too
low.

 

If
you create your database with Database Configuration Assistant (DBCA)
and choose the basic installation option, automatic memory management is
enabled. If you choose advanced installation, Database Configuration
Assistant (DBCA) enables you to select automatic memory
management.

 

 

 

ORACLE
11g AMM 的引进, 组合出来有 5 种内部存款和储蓄器管理情势.

 

   
自动内部存款和储蓄器管理(AMM)   :
memory_target=非0,是机关内存管理,假若起初化参数 LOCK_SGA=TRUE,则
AMM 是不可用的。

   
自动分享内部存储器管理(ASMM): 在memory_target=0 and
sga_target为非0的处境下是机关内部存款和储蓄器管理

   
手工业分享内部存款和储蓄器管理      : memory_target=0 and
sga_target=0 
指定
share_pool_size 、db_cache_size 等 sga 参数

    自动 PGA
管理         : memory_target=0 and
workarea_size_policy=auto 
and PGA_AGGREGATE_TARGET=值

    手动 PGA
管理         : memory_target=0 and
workarea_size_policy=manal 
然后内定 SORT_AREA_SIZE 等 PGA 参数,一般不行使手动管理PGA。

 

 

Oracle
Database 11g

supports various memory management methods, which are chosen by
initialization parameter settings. Oracle recommends that you enable the
automatic memory management method.

 

 

  1. Automatic
    Memory Management – For Both the SGA and Instance PGA

  1. Automatic
    Shared Memory Management – For the SGA

  1. Manual
    Shared Memory Management – For the SGA

  1. Automatic
    PGA Memory Management –For the Instance PGA

  1. Manual
    PGA Memory Management – For the Instance PGA

 

 

 

 

 

ASMM切换到AMM

 

一般来讲所示,当前实验景况下活动内部存款和储蓄器管理已被剥夺(memory_target=0)

 

SQL> select * from v$version;

 

BANNER

--------------------------------------------------------------------------------

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production

PL/SQL Release 11.2.0.1.0 - Production

CORE    11.2.0.1.0      Production

TNS for Linux: Version 11.2.0.1.0 - Production

NLSRTL Version 11.2.0.1.0 - Production

 

SQL> show parameter memory_target ;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

memory_target                        big integer 0

SQL> show parameter memory_max_target;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

memory_max_target                    big integer 0

SQL> 

SQL> show parameter sga;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

lock_sga                             boolean     FALSE

pre_page_sga                         boolean     FALSE

sga_max_size                         big integer 1G

sga_target                           big integer 1G

 

 

在11g中,倘诺接纳ASMM,对应的内部存款和储蓄器分享段是开诚布公的共享段。

 

SQL> !

[oracle@DB-Server ~]$ ipcs -m

 

------ Shared Memory Segments --------

key        shmid      owner      perms      bytes      nattch     status      

0x00000000 4128770    root      644        80         2                       

0x00000000 4161540    root      644        16384      2                       

0x00000000 4194309    root      644        280        2                       

0xfc5d1940 7012369    oracle    660        1075838976 49     

 

 

正如所示,首先检查参数文件类型,然后修改参数sga_target、memory_max_target、memory_target。因为中间有个别参数为静态参数,所以在改造参数后,要求重启数据库。

 

 

 

SQL> show parameter spfile;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

spfile                               string      /u01/app/oracle/product/11.1.0

                                                 /dbhome_1/dbs/spfilegsp.ora

SQL> alter system set sga_max_size=0 scope=spfile;

 

System altered.

 

SQL> alter system set sga_target=0 scope=spfile;

 

System altered.

 

SQL> alter system set pga_aggregate_target=0 scope=spfile;

 

 

SQL> alter system set memory_max_target=1G scope=spfile;

 

System altered.

 

SQL> alter system set memory_target=1G scope=spfile;

 

System altered.

 

SQL> 

 

重启数据库后,检核查应参数。

 

SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup

ORACLE instance started.

 

Total System Global Area  517816320 bytes

Fixed Size                  2214776 bytes

Variable Size             159384712 bytes

Database Buffers          348127232 bytes

Redo Buffers                8089600 bytes

Database mounted.

SQL> show parameter memory

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

hi_shared_memory_address             integer     0

memory_max_target                    big integer 1G

memory_target                        big integer 1G

shared_memory_address                integer     0

SQL> 

 

自动内存管理(AMM)运营之后,系统分享段变为“设想”分享段。

 

[oracle@DB-Server ~]$ ipcs -m

 

------ Shared Memory Segments --------

key        shmid      owner      perms      bytes      nattch     status      

0x00000000 4128770    root      644        80         2                       

0x00000000 4161540    root      644        16384      2                       

0x00000000 4194309    root      644        280        2                       

0xfc5d1940 7077905    oracle    660        4096       0            

 

 

 

 

 

11g
MEMORY_TARGET Parameter Dependency

 

那么有个问号,自动内存管理(AMM)情势上面,sga_max_size、sga_target、memory_max_target、memory_target、pga_aggregate_target那多少个参数的关系是什么的吧?其实官方文书档案已经有详细阐释

 

If
MEMORY_TARGET is set to a non-zero value:

 

·        
If
SGA_TARGET and PGA_AGGREGATE_TARGET are set, they will be considered
the minimum values for the sizes of SGA and the PGA respectively.
MEMORY_TARGET values can range from SGA_TARGET +
PGA_AGGREGATE_TARGET to MEMORY_MAX_TARGET.

·        
If
SGA_TARGET is set and PGA_AGGREGATE_TARGET is not set, we will still
auto-tune both parameters. PGA_AGGREGATE_TARGET will be initialized to
a value of MEMORY_TARGET – SGA_TARGET.

·        
If
PGA_AGGREGATE_TARGET is set and SGA_TARGET is not set, we will still
auto-tune both parameters. SGA_TARGET will be initialized to the
minimum non-zero value of MEMORY_TARGET – PGA_AGGREGATE_TARGET and
SGA_MAX_SIZE and will auto tune its components.

·        
If
neither is set, they will be auto-tuned without any minimum or default
values. We will have a policy of distributing the total memory set by
MEMORY_TARGET parameter in a fixed ratio to the the SGA and PGA during
initialization. The policy is to give 60% to the SGA and 40% to the PGA
at startup.

 

If
MEMORY_MAX_TARGET has not been explicitly set, but MEMORY_TARGET has,
the instance automatically sets MEMORY_MAX_TARGET to the same value as
MEMORY_TARGET. If MEMORY_TARGET has not been explicitly set, but
MEMORY_MAX_TARGET has, then MEMORY_TARGET defaults to 0. After
instance startup, it then is possible to dynamically change
MEMORY_TARGET to a non-zero value, provided that it does not exceed the
value of MEMORY_MAX_TARGET.

 

If
MEMORY_TARGET is not set or set to set to 0 explicitly (default value
is 0 for 11g):

·        
If
SGA_TARGET is set we will only auto-tune the sizes of the components of
the SGA. PGA will be autotuned independent of whether it is explicitly
set or not. However, the combination of SGA and PGA will not be
auto-tuned, i.e. the SGA and PGA will not share memory and resize as
with the case of MEMORY_TARGET being set to a non-zero value.

·        
If
neither SGA_TARGET nor PGA_AGGREGATE_TARGET is set, we will follow
the same policy as we have today; PGA will be auto-tuned and the SGA
will not be auto-tuned and parameters for some of the SGA components
will have to be set explicitly (for SGA_TARGET).

·        
If
only MEMORY_MAX_TARGET is set, MEMORY_TARGET will default to 0 and we
will not auto tune the SGA and PGA. It will default to 10gR2
behavior.

·        
If
SGA_MAX_SIZE is not user set, it is internally set to
MEMORY_MAX_TARGET.

 

大家上边依旧经过试验一一验证一下:

 

1:当MEMORY_TA凯雷德GET大于0的事态下,能够设置SGA_TARGET、PGA_AGGREGATE_TAEvoqueGET的值为非0,对应的含义分别如下:

 

   
如若设置了SGA_TARGET和PGA_AGGREGATE_TATucsonGET,它们分别表示SGA的的最小值和PGA的细小值。MEMOSportageY_TAENCOREGET值的范围可以从SGA_TARGET

  • PGA_AGGREGATE_TARGET到MEMORY_MAX_TARGET。

    当然SGA_TARGET + PGA_AGGREGATE_TA福特ExplorerGET的和必须低于等于memory_target,其他,假诺同期安装了sga_target、pga_aggregate_target的值,memory_target的值必须高于等于sga_target与pga_aggregate_target之和。如下测量检验所示:

 

SQL> alter system set pga_aggregate_target=200m scope=both;

 

System altered.

 

SQL> show parameter pga_aggregate_target;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

pga_aggregate_target                 big integer 200M

SQL> 

 

 

SQL> show parameter sga;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

lock_sga                             boolean     FALSE

pre_page_sga                         boolean     FALSE

sga_max_size                         big integer 496M    #后面讲述为什么sga_max_size为什么没有被置为0

sga_target                           big integer 0

SQL> alter system set sga_target=400m scope=both;

 

System altered.

 

SQL> show parameter sga;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

lock_sga                             boolean     FALSE

pre_page_sga                         boolean     FALSE

sga_max_size                         big integer 496M

sga_target                           big integer 400M

SQL> 

图片 1

 

 

 

SQL> show parameter sga;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

lock_sga                             boolean     FALSE

pre_page_sga                         boolean     FALSE

sga_max_size                         big integer 496M

sga_target                           big integer 400M

SQL> show parameter pga_aggregate_target;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

pga_aggregate_target                 big integer 200M

SQL> alter system set memory_target=696m scope=both;

 

System altered.

 

SQL> alter system set memory_target=600m scope=both;

 

System altered.

 

SQL> alter system set memroy_target=500m scope=both;

alter system set memroy_target=500m scope=both

                 *

ERROR at line 1:

ORA-02065: illegal option for ALTER SYSTEM

 

 

SQL>  alter system set memory_target=500m scope=both;

 alter system set memory_target=500m scope=both

*

ERROR at line 1:

ORA-02097: parameter cannot be modified because specified value is invalid

ORA-00838: Specified value of MEMORY_TARGET is too small, needs to be at least 600M

 

图片 2

 

 

SQL> show parameter memory_target;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

memory_target                        big integer 600M

SQL> show parameter sga;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

lock_sga                             boolean     FALSE

pre_page_sga                         boolean     FALSE

sga_max_size                         big integer 496M

sga_target                           big integer 400M

SQL> show parameter pga

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

pga_aggregate_target                 big integer 200M

SQL> 

SQL> 

SQL> alter system set pga_aggregate_target=201m scope=both;

alter system set pga_aggregate_target=300m scope=both

*

ERROR at line 1:

ORA-02097: parameter cannot be modified because specified value is invalid

ORA-00840: PGA_AGGREGATE_TARGET cannot be modified to the specified value

 

如上测验所示,假使设置了pga_aggregate_target和sga_target,那么pga_aggregate_target

  • sga_target
    必须低于等于memory_target,另外,memory_target也亟须当先等于(pga_aggregate_target
  • sga_target)

 

假定设置了SGA_TARGET并且PGA_AGGREGATE_TA昂科雷GET未有安装,数据库照旧会活动调解那么些参数。
PGA_AGGREGATE_TA索罗德GET将被初步化为MEMO奥德赛Y_TARGET –
SGA_TARGET的值。

若果设置了PGA_AGGREGATE_TAEscortGET何况没有设置SGA_TAXC60GET,数据库还是会活动调治那多少个参数。
SGA_TA大切诺基GET将被初阶化为MEMOGL450Y_TARGET –
PGA_AGGREGATE_TASportageGET,并在这一个值和SGA_MAX_SIZE这几个距离范围内电动调度

如果SGA_TARGET和PGA_AGGREGATE_TA凯雷德GET两个都并未设置的话,则它们将被自动调谐而未有别的最小值或暗中同意值。 大家将有贰个国策,在开始化进度中,将由MEMO翼虎Y_TA奥迪Q3GET参数设置的总内部存款和储蓄器以固定的比例分配给SGA和PGA。 政策是在运营时给予SGA
百分之二十和PGA 十分之三给PGA。

 

 

2:
没有安装SGA_MAX_SIZE,不过为啥SGA_MAX_SIZE一贯有值,纵然将其设置为0或采纳reset
alter system set sga_max_size=0 scope=spfile; SGA_MAX_SIZE一向有值。官方关于SGA_MAX_SIZE的介绍如下:

 

 

SGA_MAX_SIZE
specifies the maximum size of the SGA for the lifetime of the
instance.

On
64-bit platforms and non-Windows 32-bit platforms, when either
MEMORY_TARGET or MEMORY_MAX_TARGET is specified, the default value of
SGA_MAX_SIZE is set to the larger of the two parameters. This causes
more address space to be reserved for expansion of the SGA.

On
Windows 32-bit platforms, the default value of SGA_MAX_SIZE is the
largest of the following values:

·        
 

·        
60%
of MEMORY_TARGET, if specified

·        
 

·        
60%
of MEMORY_MAX_TARGET, if specified

·        
 

·        
25%
of the total available virtual address space

 

也就是说在64位平台和非Windows 32位平台上,当指定MEMORY_TARGET或MEMORY_MAX_TARGET时,SGA_MAX_SIZE的默认值将设置为两个参数中较大的一个。 这导致更多的地址空间被保留用于SGA的扩展。

这也是之前一直让我迷惑的地方。另外,官方文档建议:当切换到AMM,即使用MEMORY_TARGET时,不应该设置参数SGA_MAX_SIZE(用于ASMM),因为这样做会修复SGA的大

小,因此与MEMORY_TARGET的预期用法相冲突。(原文:Check also for SGA_MAX_SIZE being set. When switching to AMM, i.e. using MEMORY_TARGET,

the parameter SGA_MAX_SIZE (used for ASMM) should not be set as doing so fixes the size of the SGA, and hence conflicts

with the intended use of MEMORY_TARGET.)

 

 

图片 3

 

   

SGA_MAX_SIZE的值最棒不要去修改,即使其值大于MEMO牧马人Y_MAX_TA宝马X3GET的话,就报ORA-00844 & ORA-00851
错误。如下所示

 

SQL> alter system set sga_max_size=1025M scope=spfile;

 

System altered.

SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup

ORA-00844: Parameter not taking MEMORY_TARGET into account

ORA-00851: SGA_MAX_SIZE 1090519040 cannot be set to more than MEMORY_TARGET 637534208.

SQL> 

 

 

那会儿亟待改换对应spfile的pfile文件,然后找到*.sga_max_size这些值,删除后重新生成对应的spfile,运维数据库实例就能够,当然你也得以安装其值大于MEMO福睿斯Y_TARGET即可。

 

 

AMM切换到ASMM

 

SQL> show parameter target;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

archive_lag_target                   integer     0

db_flashback_retention_target        integer     1440

fast_start_io_target                 integer     0

fast_start_mttr_target               integer     0

memory_max_target                    big integer 1552M

memory_target                        big integer 1552M

parallel_servers_target              integer     16

pga_aggregate_target                 big integer 0

sga_target                           big integer 0

SQL> alter system set memory_max_target=0 scope=spfile;

 

System altered.

 

SQL> alter system set memory_target=0 scope=spfile;

 

System altered.

 

SQL> alter system set pga_aggregate_target=200m scope=spfile;

 

System altered.

 

SQL> alter system set sga_max_size=1g scope=spfile;

 

System altered.

 

SQL> alter system set sga_target=1g scope=spfile;

 

System altered.

 

SQL> 

 

 

SQL> startup

ORA-00843: Parameter not taking MEMORY_MAX_TARGET into account

ORA-00849: SGA_TARGET 1073741824 cannot be set to more than MEMORY_MAX_TARGET 0.

SQL> 

 

变迁对应的spfile的pfile文件,然后删除memory_max_target和memory_target两个参数后,然后生成对应的spfile,最终重启数据库实例就能够。

 

SQL>
create pfile from spfile;

 

File
created.

 

 

*.memory_max_target=0

*.memory_target=0

 

SQL>
create spfile from pfile;

 

File
created.

 

SQL>

 

 

选择AMM还是HugePages

 

ORACLE
11g始发推出AMM,它是ORACLE在ASMM的底子上的愈发内部存款和储蓄器管理自动化的朝梁暮晋。ASMM是全自动管理SGA,而AMM则是将SGA与PGA联合起来活动管理、调节。只供给设置memory_target四个参数就足以做到全套数据库实例内部存储器的布置。不过那么些功能没被普及采纳,因为AMM最大的主题材料在于无法利用标准大页。不常候为了利用标准大页成效,大概某些系统会禁止使用AMM.那么到底是用AMM还是使用大页呢?非常多少人(大师)侧向利用大页作用而非AMM,关于这一个能够参谋下边博文

 

MEMORY_TARGET (SGA_TARGET) or HugePages – which to
choose?

AMM and Linux Huge
Pages

Oracle Memory Management and
HugePage

 

 

如何从AMM切换到HugePage,能够参照官方文书档案(ID
2128928.1)

 

How
To Convert A Database Using AMM (Automatic Memory Management) To A
Database That Has Been Configured With Hugepage

 

 

参照他事他说加以考察资料:

 

http://blog.ronnyegner-consulting.de/2010/03/31/memory_target-sga_target-or-hugepages-which-to-choose/

https://docs.oracle.com/cd/E18283_01/server.112/e17110/initparams230.htm

http://www.dba-oracle.com/t_amm_automatic_memory.htm

https://docs.oracle.com/cd/B28359\_01/server.111/b28310/memory003.htm\#ADMIN11011

https://www.jianshu.com/p/9715280a4ced

http://oracle-help.com/oracle-database/relationship-memory\_target-sga\_target-pga\_aggregate\_target/

https://support.oracle.com/epmos/faces/DocumentDisplay?\_afrLoop=275836827924018&id=443746.1&\_afrWindowMode=0&\_adf.ctrl-state=149nyur949\_198

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