#uname -a
Linux inc-dba-crm-36-17 2.6.9-67.ELsmp #1 SMP Wed Nov 7 13:56:44 EST 2007 x86_64 x86_64 x86_64 GNU/Linuxn

kernel.shmmax = 4294967295
kernel.shmall = 2097152
数据库版本11.1.0.7

show parameter sga_ta

NAME                               TYPE                VALUE
------------------------------------ ---------------------- ------------------------------
sga_target                         big integer          1360M

1.3G的SGA，4G最大内存段的设置。按照常理不会分段。

#sysresv
IPC Resources for ORACLE_SID "crmgsb" :
Shared Memory:
ID             KEY
4685829       0x00000000
4718598       0x00000000
4751367       0x00000000
4784136       0x22c33c78
Semaphores:
ID             KEY
26869793       0x51e6c3a0
26902562       0x51e6c3a1
26935331       0x51e6c3a2
26968100       0x51e6c3a3
27000869       0x51e6c3a4
27033638       0x51e6c3a5
27066407       0x51e6c3a6
27099176       0x51e6c3a7
27131945       0x51e6c3a8
27164714       0x51e6c3a9
27197483       0x51e6c3aa
27230252       0x51e6c3ab
27263021       0x51e6c3ac
27295790       0x51e6c3ad
27328559       0x51e6c3ae
27361328       0x51e6c3af
27394097       0x51e6c3b0
Oracle Instance alive for sid "crmgsb"

ipcs -ma

------ Shared Memory Segments --------
key       shmid    owner    perms    bytes    nattch    status
0x00000000 4685829 oracle 660       654311424  1058
0x00000000 4718598 oracle 660       402653184  1058
0x00000000 4751367 oracle 660       385875968  1058
0x22c33c78 4784136 oracle 660       2097152 1058

可是很明显实例CRMGSB被分了4段共享内存。

如果关掉NUMA，重启数据库，则共享内存分段问题不再出现。
alter system set "_enable_numa_optimization"=false scope=spfile;

#ipcs -m

------ Shared Memory Segments --------
key       shmid    owner    perms    bytes    nattch    status
0x22c33c78 4947972 oracle 660       1428160512 646

不知道numa跟共享内存分段的联系是什么？大家讨论讨论

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共享内存分段问题

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