如题，最近在安装RAC时，遇到了一个问题，主机上CPU按core来算的话，为128：
#cat /proc/cpuinfo |grep pro|wc -l
128
在执行root.sh的时候，asm报4031共享内存不足的问题，这种问题，从直觉上来讲，就是要调整参数或者做某种设置，随后查询metalink发现问题所在，需要上调memory_target参数，之所以出现这个问题，是因为在新的版本中，oracle的默认参数发生了变化，详见下文：
Unable To Start ASM (ORA-00838 ORA-04031) On 11.2.0.3/11.2.0.4 If OS CPUs # > 64. (文档 ID 1416083.1)

In this Document

Symptoms

Cause

Solution

Community Discussions

References

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.1 to 12.1.0.2 [Release 11.2 to 12.1]
Information in this document applies to any platform.

Symptoms

1) ASM 11.2.0.3/11.2.0.4 configuration on Solaris SPARC T4-4 Server with 128 CPUs & RAM = 128 GB.

2) If the 128 CPUs are enabled, then ASM instance is unable to start due to the next errors:

ORA-00838: Specified value of MEMORY_TARGET is too small, needs to be at least 1328M
ORA-01078: failure in processing system parameters

[main] [ 2012-01-21 18:26:28.986 COT ] [UsmcaLogger.logException:174] ORA-04031: unable to allocate 32 bytes of shared memory ("shared pool","SELECT DECODE(null,'','Total...","SQLA","tmp")

3) But if only 64 CPUs are enabled, then ASM instance starts without problems.

4) On release 11.2, ASM uses Automatic Memory Management (AMM) by default, therefore MEMORY_MAX_TARGET & MEMORY_TARGET have the default values = 272 MB (in the ASM instance):

MEMORY_MAX_TARGET = 272M
MEMORY_TARGET = 272M

5) And so, the SGA in the ASM instance has the same value (900 MB):

SQL> show sga

Total System Global Area 283930624 bytes
Fixed Size                  2227664 bytes
Variable Size             256537136 bytes
ASM Cache                  25165824 bytes

Cause

In 11.2.0.3/11.2.0.4, the "PROCESSES" parameter will be default to "available CPU cores * 80 + 40" (in the ASM spfile). As the default value for "MEMORY_TARGET" is based on "PROCESSES", it can be insufficient if there is a large number of CPU cores or large number of diskgroups which could cause issues (i.e. Grid Infrastructure stack fails to stop with ORA-04031 etc) per Bug:13605735 & Bug:12885278, it is recommended to increase the value of MEMORY_MAX_TARGET & MEMORY_TARGET before upgrading/installing to 11.2.0.3/11.2.0.4 (does not apply to 10g ASM).

Solution

1) Connect to the ASM instance(s) and increase the MEMORY_MAX_TARGET & MEMORY_TARGET as follow (3GB or 4GB will be enough):

SQL> alter system set MEMORY_MAX_TARGET=4096m scope=spfile SID='*';
SQL> alter system set MEMORY_TARGET=3072m scope=spfile SID='*';

Note: The number 1536m has proven to be sufficient for most environment, the change will not be effective until next restart.

2) Restart the ASM instances to apply the changes.

3) Then enable all the CPUs (e.g. total = 128) in your system:

bash-3.00# prtdiag -v|grep SPARC-T4 | grep on-line | wc -l
128

Important Note 1:

In 11.2.0.3/11.2.0.4, we increase the default PROCESSES based on the number of CPU cores, and the default MEMORY_TARGET is based on PROCESSES.   If in 11.2.0.2, customers explicitly set MEMORY_TARGET to some value that may not be big enough for 11.2.0.3/11.2.0.4, when they upgrade to 11.2.0.3/11.2.0.4, ASM will fail to start with error "memory_target is too small".    We should add additional check for MEMORY_TARGET during the upgrade prerequisite check.

You can unset MEMORY_TARGET so that ASM can use the default value, but if MEMORY_TARGET is explicitly set, please make sure it's large enough, following the next rules:

1) If PROCESSES parameter is explicitly set:

The MEMORY_TARGET should be set to no less than:

      256M + PROCESSES * 132K (64bit)

or

      256M + PROCESSES * 120K (32bit)

2) If PROCESSES parameter is not set:

The MEMORY_TARGET should be set to no less than:

256M + (available_cpu_cores * 80 + 40) * 132K (64bit)

or

256M + (available_cpu_cores * 80 + 40) * 120K (32bit)

Important Note 2:

If this problem (ORA-4031 error) is occurring during a brand new ASM (11.2.0.3 or 11.2.0.4) installation/configuration (e.g. when running root.sh to start the ASM instance) and many CPUs/Cores are enabled (above 4), then temporally disable most of them and leave just few enabled (about 2 or 4), as the following example (64 CPUs are present and enabled):

1) Ask your SA to disable 62 CPUs and leave enable only 2 of 64.

2) Verify only 2 CPUs were/are enabled using the next commands:

# kstat cpu_info | grep core_id | awk '{ print $2}' | uniq | wc -l

# prtdiag -v|grep SPARC-T4 | grep on-line | wc -l

3) Run root.sh again to start the ASM services/instances and complete the installation.

4) Once the ASM instances are created and running, then increase the SGA (AMM) in the ASM instances as follows (exact same values below):

SQL> alter system set MEMORY_MAX_TARGET=4096m scope=spfile;
SQL> alter system set MEMORY_TARGET=1536m scope=spfile;

5) Restart the ASM instances and check the AMM values:

SQL> show parameter MEMORY_MAX_TARGET
SQL> show parameter MEMORY_TARGET

6) Ask your SA to enable back the other 62 CPUs.

7) Restart CRS or HAS and make sure the ASM instances start.

关于这个问题，还可以参考另外一篇文档，说的比较详细：ASM & Shared Pool (ORA-4031) (文档 ID 437924.1)

ITPub博客

128C下安装oracle 11.2.0.4 RAC遇到4031报错。

Applies to:

Symptoms

Cause

Solution

最新文章