今天遇到一个问题，Oracle dbca时报错：ORA-12547: TNS:lost contact
环境：
OS:RHEL6.5 x86-64bit
DB:11.2.0.4 for Linux 86-64bit
思路：
DBCA报错，首先看DBCA的日志，日志中也是报ORA-12547: TNS:lost contact
于是再sqlplus / as sysdba敲回车，也是报ORA-12547: TNS:lost contact，基于之前的工程经验，先到bdump下找trc文件，不过在bdump下是没有任何trc生成的。再到/u01/app/oracle/product/11.2.0/db_1/rdbms/log下找trc文件，果然找到了：
[oracle@dg1 log]$ pwd
/u01/app/oracle/product/11.2.0/db_1/rdbms/log
[oracle@dg1 log]$ ls -lrt
total 9808
-rw-r-----. 1 oracle oinstall 401207 Feb 1 16:16 dbua1557284_ora_8053.trc
-rw-r-----. 1 oracle oinstall 401207 Feb 1 16:16 dbua1557284_ora_8062.trc
-rw-r-----. 1 oracle oinstall 401207 Feb 1 16:16 dbua1557284_ora_8065.trc
-rw-r-----. 1 oracle oinstall 401373 Feb 1 16:18 dg1_ora_8227.trc
-rw-r-----. 1 oracle oinstall 401228 Feb 1 16:26 dg1_ora_2701.trc
-rw-r-----. 1 oracle oinstall 401228 Feb 1 16:26 dg1_ora_2706.trc
-rw-r-----. 1 oracle oinstall 401410 Feb 1 16:27 dg1_ora_2715.trc
-rw-r-----. 1 oracle oinstall 401228 Feb 1 16:27 dg1_ora_2722.trc
-rw-r-----. 1 oracle oinstall 401244 Feb 1 16:31 dbua3144297_ora_2792.trc
-rw-r-----. 1 oracle oinstall 401244 Feb 1 16:31 dbua3144297_ora_2801.trc
-rw-r-----. 1 oracle oinstall 401244 Feb 1 16:31 dbua3144297_ora_2804.trc
-rw-r-----. 1 oracle oinstall 401410 Feb 1 16:34 dg1_ora_2930.trc
-rw-r-----. 1 oracle oinstall 401341 Feb 1 17:27 dg1_ora_3181.trc
-rw-r-----. 1 oracle oinstall 401090 Feb 1 17:27 dg1_ora_3187.trc
-rw-r-----. 1 oracle oinstall 401341 Feb 1 17:27 dg1_ora_3190.trc
-rw-r-----. 1 oracle oinstall 401090 Feb 1 17:28 dg1_ora_3205.trc
-rw-r-----. 1 oracle oinstall 401341 Feb 1 17:28 dg1_ora_3210.trc
-rw-r-----. 1 oracle oinstall 401090 Feb 1 17:28 dg1_ora_3214.trc
-rw-r-----. 1 oracle oinstall 401090 Feb 1 17:36 dg1_ora_3313.trc
-rw-r-----. 1 oracle oinstall 401341 Feb 1 17:37 dg1_ora_3329.trc
-rw-r-----. 1 oracle oinstall 401090 Feb 1 17:37 dg1_ora_3341.trc
-rw-r-----. 1 oracle oinstall 401090 Feb 1 17:37 dg1_ora_3344.trc
-rw-r-----. 1 oracle oinstall 401341 Feb 1 17:40 dg1_ora_3369.trc
-rw-r-----. 1 oracle oinstall 401341 Feb 1 17:40 dg1_ora_3375.trc
-rw-r-----. 1 oracle oinstall 401090 Feb 1 17:40 dg1_ora_3378.trc
[oracle@dg1 log]$
[oracle@dg1 log]$ vi dg1_ora_3369.trc
Dump file /u01/app/oracle/product/11.2.0/db_1/rdbms/log/dg1_ora_3369.trc
*** 2016-02-01 17:40:23.652
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
ORACLE_HOME = /u01/app/oracle/product/11.2.0/db_1
System name: Linux
Node name: dg1
Release: 2.6.32-431.el6.x86_64
Version: #1 SMP Sun Nov 10 22:19:54 EST 2013
Machine: x86_64
Instance name: dg1
Redo thread mounted by this instance: 0 <none>
Oracle process number: 0
Unix process pid: 3369, image: oracle@dg1
*** 2016-02-01 17:40:23.652
skgm error 27135: errno = 0, info = 0, 0, 0, 0, 1048576, 2097152, 0
skgm error 27135: errno = 0, info = 0, 0, 0, 0, 1048576, 2097152, 0
*** 2016-02-01 17:40:23.654
Exception [type: SIGSEGV, Address not mapped to object] [ADDR:0x3D8] [PC:0x95BE6EB, opiodr()+11347] [flags: 0x0, count: 1]
Registers:
%rax: 0x000000000c0ea630 %rbx: 0x000000000c0ea638 %rcx: 0x0000000000000000
%rdx: 0x0000000000000000 %rdi: 0x000000000c0ccba0 %rsi: 0x00007fffa308e250
%rsp: 0x00007fffa308d970 %rbp: 0x00007fffa308e440 %r8: 0x00007fffa308d970
%r9: 0x00007fffa308e440 %r10: 0x00007fffa308c600 %r11: 0x00007fab40ec1538
%r12: 0x000000000000003c %r13: 0x0000000000000004 %r14: 0x00007fffa308e6f8
%r15: 0x0000000000000002 %rip: 0x00000000095be6eb %efl: 0x0000000000010246
opiodr()+11325 (0x95be6d5) lea (%rax,%rbx),%rdx
opiodr()+11329 (0x95be6d9) mov %rdx,(%rcx,%rbx)
opiodr()+11333 (0x95be6dd) mov 0x2b34a84(%rip),%rax
opiodr()+11340 (0x95be6e4) mov 0x178(%rax),%rdx
> opiodr()+11347 (0x95be6eb) movzwl 0x3d8(%rdx),%ecx
opiodr()+11354 (0x95be6f2) test $0x100,%ecx
opiodr()+11360 (0x95be6f8) jz 0x95bc8c7
opiodr()+11366 (0x95be6fe) mov -0x18(%rbp),%eax
opiodr()+11369 (0x95be701) cmp $60,%eax
*** 2016-02-01 17:40:23.660
dbkedDefDump(): Starting a non-incident diagnostic dump (flags=0x1, level=3, mask=0x0)
----- Error Stack Dump -----
ORA-07445: exception encountered: core dump [opiodr()+11347] [SIGSEGV] [ADDR:0x3D8] [PC:0x95BE6EB] [Address not mapped to object] []
ORA-27135: Operating System hard stack limit is set too low ----------->>>>>>>注意此处
Additional information: 1048576
Additional information: 2097152
----- SQL Statement (None) -----
Current SQL information unavailable - no SGA.
以下省略。。。
最后确认，是/etc/security/limits.conf文件的问题：