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Oracle 12c on CentOS

Installing Oracle DB 12c on a virtual machine for testing and developing purposes has it advantages. The installation is quite invasive and when it’s done in a virtualbox, it does no harm to your host system at work, which is btw. Windows and a total mess itself. If you follow the installation instructions and restarted the virtual machine I notice few things that didn’t work by trying to access the database from a SQL client.

First of all, the Oracle DB instance is not automatically started. IMHO it is good, since I don’t frequently use Oracle DB. If used, it allocates a lot of resources of my notebook.

Environment Settings

The Oracle user needs some environment variables set, to work properly. I named the file oracle_schrott

TMPDIR=$TMP; export TMPDIR
ORACLE_BASE=/var/opt/oracle; export ORACLE_BASE
ORACLE_HOME=$ORACLE_BASE/product/12.1.0/dbhome_1; export ORACLE_HOME
ORACLE_SID=saa; export ORACLE_SID
PATH=$ORACLE_HOME/bin:$PATH; export PATH
LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib:/usr/lib64; export LD_LIBRARY_PATH
CLASSPATH=$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib; export CLASSPATH

You can source this file for instance within your .bash_profile.

[vinh@localhost ~]$ cat .bash_profile
# .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
        . ~/.bashrc
fi

# User specific environment and startup programs

source ~/oracle_schrott
PATH=$PATH:$HOME/.local/bin:$HOME/bin
export PATH

Start Instance

If you have the proper settings you have the command dbstart available. The proper call is however this:

vinh@localhost ~]$ dbstart $ORACLE_HOME

Now you can connect to the Oracle DB system

[vinh@localhost ~]$ sqlplus / as sysdba
SQL*Plus: Release 12.1.0.2.0 Production on Thu Dec 29 17:46:26 2016
Copyright (c) 1982, 2014, Oracle.  All rights reserved.
Connected to an idle instance.

:question: Idle instance. Yes you need to startup.

SQL> startup
ORACLE instance started.

Total System Global Area 2432696320 bytes
Fixed Size                  2927288 bytes
Variable Size             654312776 bytes
Database Buffers         1761607680 bytes
Redo Buffers               13848576 bytes
Database mounted.
Database opened.

SQL> select current_date from dual;

CURRENT_D
---------
29-DEC-16

If you can startup, you can also shutdown.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

Connectivity

If you add the natting rule to virtualbox for the db port 1521, you will notice a connection problem. CentOS needs to be configured for that. First, check!

[root@localhost ~]# firewall-cmd --get-active-zones
public
  interfaces: enp0s3

Add Oracle ports

[root@localhost ~]# firewall-cmd --zone=public --add-port=1521/tcp --add-port=5500/tcp --add-port=5520/tcp --add-port=3938/tcp --permanent
success

[root@localhost ~]# firewall-cmd --reload
success

[root@localhost ~]# firewall-cmd --list-ports
1521/tcp 5520/tcp 3938/tcp 5500/tcp

After that you can use the DB from the Windows host.