OracleStudy case-view shared memory through IPCS "strange phenomenon" in Oracle11gR2 environment, through ipcs command to view shared memory, it was found that the memory allocated to Oracle is only 4096 Bytes, this problem has never been found in the Oracle10g environment! [Root @ rh6 ~] # Ipcs-a ------ SharedMemorySegments -------- keyshm
Oracle Study Case-view shared memory through IPCS "strange phenomenon" in Oracle 11gR2 environment, through the ipcs command to view the shared memory, it was found that the memory allocated to Oracle is only 4096 Bytes, this problem has never been found in Oracle 10 Gb environment! [Root @ rh6 ~] # Ipcs-a ------ SharedMemorySegments -------- keyshm
Case Study of Oracle Study-view the "strange phenomenon" of shared memory through IPCS"
In the Oracle 11gR2 environment, using the ipcs command to view the shared memory, we found that the memory allocated to Oracle is only 4096 Bytes, and this problem was never found in the Oracle 10g environment!
[root@rh6 ~]# ipcs -a------ Shared Memory Segments --------key shmid owner perms bytes nattch status0x00000000 0 root 644 52 20x00000000 32769 root 644 16384 20x00000000 65538 root 644 268 20x00000000 98307 gdm 600 393216 2 dest0x00000000 131076 gdm 600 393216 2 dest0x00000000 163845 gdm 600 393216 2 dest0x00000000 196614 gdm 600 393216 2 dest0x00000000 229383 gdm 600 393216 2 dest0x4b4218ec 557064 oracle 660 4096 0------ Semaphore Arrays --------key semid owner perms nsems0x00000000 0 root 600 10x00000000 98305 root 600 10x000000a7 327682 root 600 10xbe61d9cc 983043 oracle 660 154------ Message Queues --------key msqid owner perms used-bytes messages
Database Version:
16:27:09 SYS@ test3 >select * from v$version;BANNER--------------------------------------------------------------------------------Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - ProductionPL/SQL Release 11.2.0.1.0 - ProductionCORE 11.2.0.1.0 ProductionTNS for Linux: Version 11.2.0.1.0 - ProductionNLSRTL Version 11.2.0.1.0 - Production
The following two parameters are used to automatically manage the memory of cycle 11g:
16:27:19 SYS@ test3 >show parameter memNAME TYPE VALUE------------------------------------ ----------- ------------------------------hi_shared_memory_address integer 0memory_max_target big integer 300Mmemory_target big integer 300Mshared_memory_address integer 0
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1. Will it be related to the memory_max_target parameter? Set it to 0 and restart the database.
16:28:11 SYS@ test3 >alter system set memory_target=0 ;System altered.16:36:44 SYS@ test3 >show parameter memNAME TYPE VALUE------------------------------------ ---------------------- ------------------------------hi_shared_memory_address integer 0memory_max_target big integer 300Mmemory_target big integer 0shared_memory_address integer 016:30:51 SYS@ test3 >startup force ;ORACLE instance started.Total System Global Area 313860096 bytesFixed Size 1336232 bytesVariable Size 205524056 bytesDatabase Buffers 100663296 bytesRedo Buffers 6336512 bytesDatabase mounted.Database opened.
Let's look at the shared memory:
[oracle@rh6 ~]$ ipcs -a------ Shared Memory Segments --------key shmid owner perms bytes nattch status0x00000000 0 root 644 52 20x00000000 32769 root 644 16384 20x00000000 65538 root 644 268 20x4b4218ec 622600 oracle 660 4096 0------ Semaphore Arrays --------key semid owner perms nsems0xbe61d9cc 1114115 oracle 660 154------ Message Queues --------key msqid owner perms used-bytes messages
We found that the shared memory allocated to Oracle is still small, which does not seem to be a problem with the memory_target parameter!
2. Try to adjust the memory_max_target parameter and restore it to the default value of the system:
16:39:49 SYS@ test3 >alter system set sga_max_size=300m scope=spfile;System altered.16:40:06 SYS@ test3 >alter system reset memory_max_target scope=spfile sid='*';System altered.16:40:40 SYS@ test3 >startup force nomount;ORACLE instance started.Total System Global Area 313860096 bytesFixed Size 1336232 bytesVariable Size 205524056 bytesDatabase Buffers 100663296 bytesRedo Buffers 6336512 bytes16:40:52 SYS@ test3 >show parameter memNAME TYPE VALUE------------------------------------ ---------------------- ------------------------------hi_shared_memory_address integer 0memory_max_target big integer 0memory_target big integer 0shared_memory_address integer 016:40:59 SYS@ test3 >show parameter sgaNAME TYPE VALUE------------------------------------ ---------------------- ------------------------------lock_sga boolean FALSEpre_page_sga boolean FALSEsga_max_size big integer 300Msga_target big integer 180M
View the system shared memory:
[oracle@rh6 ~]$ ipcs -a------ Shared Memory Segments --------key shmid owner perms bytes nattch status0x00000000 0 root 644 52 20x00000000 32769 root 644 16384 20x00000000 65538 root 644 268 20x4b4218ec 884744 oracle 660 316669952 16------ Semaphore Arrays --------key semid owner perms nsems0xbe61d9cc 1638403 oracle 660 154------ Message Queues --------key msqid owner perms used-bytes messages
It seems that the memory_max_target parameter is set. As a result, the memory allocated to Oracle is 4096 Bytes through ipcs!