We start with installation of packages

Confirm if you install have minimal 16G swap cache, on system.

free -m

Almost installations have a minimal of 16G for swap, my system for example have a 128G memory – recently many docs confirms 16G of swap is ok for all memory configurations.

Make the update for the entire system, update the packages you made this commands below like a root.

yum update
yum install oracle-rdbms-server-11gR2-preinstall.x86_64
Change the user oracle password:
passwd oracle
Please verify the security by selinux files, modify this entry:
/etc/selinux/config
modify to 
SELINUX=disabled
attention: do not confuse this line, pay attention.
reboot the system
If you not reboot the system you receive messages like, permission denied to disable services below.
And stop the services, because this services is consuming memory and resources (cpu).
systemctl stop firewalld
systemctl stop iptables
systemctl disable firewalld
systemctl disable iptables
systemctl disable atd
systemctl disable bluetooth
systemctl disable postfix
systemctl disable sound
systemctl disable anacron 
systemctl disable atd 
systemctl disable cups 
systemctl disable cups-config-daemon 
systemctl disable gpm 
systemctl disable iptables 
systemctl disable kudzu 
systemctl disable lvm2-monitor 
systemctl disable microcode_ctl 
systemctl disable sendmail 
systemctl disable smartd 
systemctl disable auditd 
systemctl disable avahi-daemon 
systemctl disable bluetooth 
systemctl disable firstboot 
systemctl disable hidd 
systemctl disable ip6tables 
systemctl disable mcstrans 
systemctl disable mdmonitor 
systemctl disable pcscd 
systemctl disable rawdevices 
systemctl disable readahead_early 
systemctl disable readahead_later 
systemctl disable restorecond 
systemctl disable setroubleshoot 
systemctl disable yum-updatesd 
systemctl disable nfs 
systemctl disable autofs on
systemctl disable cpuspeed on
systemctl disable haldaemon on
systemctl disable irqbalance on
systemctl disable messagebus on
systemctl disable netfs on
systemctl disable nfslock on
systemctl disable rpcgssd on
systemctl disable rpcidmapd on
systemctl disable portmap on
The old model (before Oracle Linux 7 or RHEL 7)
chkconfig anacron off
chkconfig atd off
chkconfig cups off
chkconfig cups-config-daemon off
chkconfig gpm off
chkconfig iptables off
chkconfig kudzu off
chkconfig lvm2-monitor off
chkconfig microcode_ctl off
chkconfig sendmail off
chkconfig smartd off
chkconfig auditd off
chkconfig avahi-daemon off
chkconfig bluetooth off
chkconfig firstboot off
chkconfig hidd off
chkconfig ip6tables off
chkconfig mcstrans off
chkconfig mdmonitor off
chkconfig pcscd off
chkconfig rawdevices off
chkconfig readahead_early off
chkconfig readahead_later off
chkconfig restorecond off
chkconfig setroubleshoot off
chkconfig yum-updatesd off
chkconfig nfs off
chkconfig autofs on
chkconfig cpuspeed on
chkconfig haldaemon on
chkconfig irqbalance on
chkconfig messagebus on
chkconfig netfs on
chkconfig nfslock on
chkconfig rpcgssd on
chkconfig rpcidmapd on
chkconfig portmap on
Reboot the system for this services not startup again.
su – oracle
and create .bash_profile
add this on your file:
echo “###############################################”
echo “#         BANCO     SCRIPT    AMBIENTE        #”
echo “###############################################”
export NLS_LANG=”BRAZILIAN PORTUGUESE_BRAZIL.WE8MSWIN1252″
export ORACLE_SID=prd
export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1
export PATH=$ORACLE_HOME/bin:$PATH
export ORACLE_UNQNAME=prd