本机IP地址：192.168.1.163
[oracle@rtest ~]$ sqlplus /nolog
SQL*Plus: Release 10.2.0.2.0 - Production on Sun May 4 19:32:13 2014
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
@>conn sys/oracle
ERROR:
ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux Error: 2: No such file or directory
产生ORA-01034和ORA-27101是因为数据库没有启动，需要有sysdba进入启动数据库。
#############################################################################################################
@>conn sys/oracle as sysdba
Connected to an idle instance.
SYS@TEST0422>startup
ORA-00600: internal error code, arguments: [keltnfy-ldmInit], [46], [1], [], [], [], [], []
SYS@TEST0422>startup
ORA-24324: service handle not initialized
ORA-01041: internal error. hostdef extension doesn't exist
产生以上ORA-00600根本原因是服务器hostname没有正确配置，通过hostname命令得到的主机名无法ping通，Oracle10g认为主机无法达到所以启动数据库报错。
解决方法：将hostname添加到/etc/hosts文件中，并且修改/etc/sysconfig/network，让hostname保持一致。重新启动数据库。
解决方法：将hostname添加到/etc/hosts文件中，并且修改/etc/sysconfig/network，让hostname保持一致。重新启动数据库。
[root@rtest ~]# vi /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=rtest.localdomain
[root@rtest ~]# vi /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 ocm1.localdomain ocm1 localhost.localdomain localhost
::1 localhost6.localdomain6 localhost6
192.168.1.163 rtest.localdomain rtest
~
之前是192.168.1.161 ocm1.localdomian ocm1
###########################################################################################
[oracle@rtest ~]$ sqlplus "/as sysdba"
SQL*Plus: Release 10.2.0.2.0 - Production on Sun May 4 19:43:40 2014
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
Connected to an idle instance.
SYS@TEST0422>startup
ORACLE instance started.
Total System Global Area 285212672 bytes
Fixed Size 1260420 bytes
Variable Size 92275836 bytes
Database Buffers 188743680 bytes
Redo Buffers 2932736 bytes
Database mounted.
Database opened.
SYS@TEST0422>