Wednesday, June 16, 2021

Oracle 19.11 failed with "Out of memory" on AIX

When applying Oracle GI Release Update on AIX, command " -postpatch" failed with "Out of memory" as following
[root@host01]# /u01/app/oracle/product/19.0.0/grid_1/crs/install/ -postpatch
Using configuration parameter file: /u01/app/oracle/product/19.0.0/grid_1/crs/install/crsconfig_params
The log of current session can be found at:
Out of memory!
Out of memory!
Out of memory!
/u01/app/oracle/product/19.0.0/grid_1/crs/install/[137]: 7930494 Segmentation fault(coredump)
The command '/u01/app/oracle/product/19.0.0/grid_1/perl/bin/perl -I/u01/app/oracle/product/19.0.0/grid_1/perl/lib -I/u01/app/oracle/product/19.0.0/grid_1/crs/install -I/u01/app/oracle/product/19.0.0/grid_1/xag /u01/app/oracle/product/19.0.0/grid_1/crs/install/ -postpatch' execution failed

The error is coming from the perl process (script executing the root configuration scripts, the perl process does not have enough memory(especially data segments) during the script execution.

Technically, the "Out of memory" error could be seen on AIX while running Oracle 19c perl scripts for root configuration. These perl scripts are usually executed/called by DBA with sh script,,,, etc. Although the error was hard to see before, it is becoming popular since Oracle GI RU 19.11 was released.

It is caused by OS memory allocation method. On AIX, the number of data segments that a process is allowed to use also limits the process memory size. The default number of data segments is one. The size of a data segment is 256 MB. Data segments are shared for both data and stack. The maximum number of additional data segments a process can use is eight (2GB). The number of segments that a process can use for data is controlled by the LDR_CNTRL environment variable. It is defined in the parent process of the process that is to be affected.

Therefore, we are able to fix the issue by increasing process memory size through increasing value of environment variable LDR_CNTRL. For example, the following defines eight additional data segments

export LDR_CNTRL=MAXDATA=0x80000000
<root script>

  <root script> is what you have to run as root which got "Out of memory". In my case, it is " -postpatch".
  unset command remove (unset) the LDR_CNTRL environment variable, so that it does not unintentionally affect other processes.

Some argumentative guy says eight additional data segments (2GB) is too large, ok, you can set to 4 as following

export LDR_CNTRL=MAXDATA=0x40000000

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