Switch between Oracle11gAMM and ASMM

By default, Oracle11g uses AMM. During the installation process, specify the percentage of memory used by Oracle. This value is used as MEMORY_TARGET and MEMORY_MAX.

By default, Oracle 11g uses AMM. During the installation process, specify the percentage of memory used by Oracle. This value is used as MEMORY_TARGET and MEMORY_MAX.

Oracle is now evolving towards intelligence. If we are looking for Oracle books in the 8i/9i era, it is very important to configure appropriate database memory pools. However, after entering 10 Gb, automatic memory pool adjustment becomes an important Oracle feature.

At 10 Gb, Oracle introduced ASMM (Automatic Shared Memory Management), implementing self-adjustment of the internal structure of Oracle SGA and PGA. After entering 11 GB, AMM (Automatic Memory Management) implements the MEMORY_TARGET parameter, and comprehensively handles the SGA and PGA planning.

By default, Oracle 11g uses AMM. During the installation process, specify the percentage of memory used by Oracle. This value is used as the initial values of MEMORY_TARGET and MEMORY_MAX_TARGET. If the two parameters are set to a non-zero value, Oracle uses the AMM management policy.

At the same time, if we set these two parameters to 0, AMM will be automatically disabled. After the values of SGA_TARGET and PGA_AGGREGATE_TARGET are non-zero, Oracle automatically degrades to use the ASMM feature.

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Incomplete Oracle database recovery

Time-point-based Incomplete recovery for RMAN backup and recovery

In archive mode, the same backup of RMAN is used twice for Incomplete recovery.

RMAN full database [full recovery/Incomplete recovery]

CentOS 5.2x86 install Oracle 11g R2 notes

Install Oracle 11gR2 (x64) in CentOS 6.4)

Steps for installing Oracle 11gR2 in vmwarevm

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This article briefly introduces the switching between AMM and ASMM.

1. experiment environment Introduction

Select 11.2.0.3 for the test. The current status is ASMM.

SQL> select * from v $ version;

BANNER

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

Oracle Database 11g Enterprise Edition Release 11.2.0.3.0-Production

PL/SQL Release 11.2.0.3.0-Production

CORE 11.2.0.3.0 Production





Currently, MEMORY_TARGET is set to zero and AMM is not enabled.





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 0

Memory_target big integer 0

Parallel_servers_target integer 16

Pga_aggregate_target big integer 108 M

Sga_target big integer 252 M





2. From ASMM to AMM



In the 11g, if ASMM is used, the corresponding memory share segment is a real share segment.





[Oracle @ SimpleLinux ~] $ Ipcs-m



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

Key shmid owner perms bytes nattch status

0x00000000 32768 oracle 640 4194304 32

0x00000000 65537 oracle 640 260046848 32

0x01606d30 98306 oracle 640 4194304 32

Below we will adjust the parameters. Here I have a suggestion that the failure in starting umount is often caused by improper parameter modification. Before modifying the parameters, you can use create pfile to back up the parameters to speed up system repair when a fault occurs.

SQL> show parameter spfile

NAME TYPE VALUE

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

Spfile string/u01/app/oracle/dbs/spfileora11g. ora



SQL> create pfile from spfile;

Done

Modify the system parameters, set the target values of sga and pga to 0, and set the target value of memory to not 0. Note: many parameters in this process are static parameters, which can be modified in spfile visibility. Then, restart the server to take effect.

SQL> alter system set memory_max_target = 360 m scope = spfile;

System altered



SQL> alter system set memory_target = 360 m scope = spfile;

System altered



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

System altered



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

System altered



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

System altered

Restart the database server and view the parameter configuration.

SQL> conn/as sysdba

Connected.

SQL> startup force

ORACLE instance started.



Total System Global Area 263651328 bytes

Fixed Size 1344284 bytes

Variable Size 176164068 bytes

Database Buffers 83886080 bytes

Redo Buffers 2256896 bytes

Database mounted.

Database opened.



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 360 M

Memory_target big integer 360 M

Parallel_servers_target integer 16

Pga_aggregate_target big integer 0

Sga_target big integer 0

After AMM is started, the system shared segment is changed to a "virtual" shared segment.

[Oracle @ SimpleLinux dbs] $ ipcs-m



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

Key shmid owner perms bytes nattch status

0x00000000 163840 oracle 640 4096 0

0x00000000 196609 oracle 640 4096 0

0x01606d30 229378 oracle 640 4096 0

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