Exellent article on the subject:

http://www.lab128.com/rac_installation_using_vb/article_text.html

several others:

http://www.freeoraclehelp.com/2011/09/oracle-11gr2-rac-installation-with-gns.html

https://access.redhat.com/sites/default/files/attachments/deploying-oracle-11gr2-rac-on-rhel6_1.1.pdf

How to stop firewall on Oracle Linux 7

# systemctl stop firewalld
# systemctl disable firewalld

To add second IP to the interface

ifconfig eth0:0 192.168.1.2 netmask 255.255.255.0 up

To delete second IP from the interface

ip addr del 212.193.105.151 dev eth0

To boot Linux in text mode:

open GRUB boot menu and edit kernel parameters string: "rhgb quiet" change for "text 3"

To reinstall XWindows:

# yum update
# yum groupinstall “X Window System”

To establish passwordless ssh connectivity:

$ ssh-copy-id <hostname>

To check status of clusterware:

# . oraenv

ORACLE_SID = [oracle] ? +ASM1
The Oracle base has been set to /u01/app/oracle

# crsctl status resource -t

Another way to check status:

# crs_stat -t

To start/stop clusterware:

crsctl start cluster -all

$ . oraenv
ORACLE_SID = [oracle] ? ractp
The Oracle base has been set to /u01/app/oracle

$ srvctl config database -d ractp
Database unique name: ractp
Database name: ractp
Oracle home: /u01/app/oracle/product/11.2.0/dbhome_1
Oracle user: oracle
Spfile: +DATA/ractp/spfileractp.ora
Domain: localdomain
Start options: open
Stop options: immediate
Database role: PRIMARY
Management policy: AUTOMATIC
Server pools: ractp
Database instances: ractp1,ractp2
Disk Groups: DATA
Mount point paths: 
Services: 
Type: RAC
Database is administrator managed

$ srvctl status database -d ractp
Instance ractp1 is running on node rac1
Instance ractp2 is running on node rac2

$ export ORACLE_SID=ractp1
[oracle@rac1 Desktop]$ sqlplus / as sysdba
SELECT inst_name FROM v$active_instances;

INST_NAME
--------------------------------------------------------------------------------
rac1.localdomain:ractp1
rac2.localdomain:ractp2

exit

Clean shutdown:

$ . oraenv
ORACLE_SID = [oracle] ? ractp
The Oracle base has been set to /u01/app/oracle

$ srvctl stop database -d ractp

Shutdown the clusterware on the first node:

# . oraenv
ORACLE_SID = [ractp1] ? +ASM1
The Oracle base remains unchanged with value /u01/app/oracle

# crsctl stop crs
...
CRS-4133: Oracle High Availability Services has been stopped.

Shutdown the clusterware on the second node:

# . oraenv
ORACLE_SID = [ractp1] ? +ASM2
The Oracle base remains unchanged with value /u01/app/oracle

# crsctl stop crs
...
CRS-4133: Oracle High Availability Services has been stopped.

Important:

After changes in network configuration (ifconfig, /etc/hosts) I would advise to start installation from the beginning. Sometimes already running installation does not see the changes.

22 ssh port is not enough for the internode connectivity. It is better to disable firewall on the nodes at all or open all TCP ports between rac nodes.

For linux the issue with running root.sh might be.

There is the doc ID 1607600.1 "Failed to start oracle-ohasd, error: Inappropriate ioctl for device" on the metalink

/opt/oracle/11.2.0/grid/crs/install/rootcrs.pl -deconfig -force -verbose

Configuring autostart of RAC services

# crsctl stat res -p

AUTO_START=restore

# crsctl modify resource "ora.ractp.db" -attr "AUTO_START=always"

# crsctl status resource ora.ractp.db -p | grep AUTO_START