How to solve ORA-27125: unable to create shared memory segment on AIX

When starting an Oracle instance on a new AIX server, the following error may occur:

ORA-27125: unable to create shared memory segment
IBM AIX RISC System/6000 Error: 1: Not owner

The situation is resolved by setting "capabilities" on the oracle operating system user, as follows:

[root@server1] lsuser -a capabilities oracle
oracle
[root@tsu0emdb02] chuser capabilities=CAP_BYPASS_RAC_VMM,CAP_PROPAGATE oracle
[root@tsu0emdb02] lsuser -a capabilities oracle
oracle capabilities=CAP_BYPASS_RAC_VMM,CAP_PROPAGATE

You can now start your instance:

server1:testdb1>sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Fri Sep 12 12:10:04 2014

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup nomount
ORACLE instance started.

Total System Global Area 5344731136 bytes
Fixed Size                  2255784 bytes
Variable Size            1392510040 bytes
Database Buffers         3942645760 bytes
Redo Buffers                7319552 bytes
SQL>