Restore CRS_HOME in 10g RAC database on Linux

This article will discuss steps to restore CRS binaries which could have been removed by mistake or require restore due to local disk failure. To ensure this, we need to have first backup of following files. You can schedule this as cron job which takes weekly/daily backup

$ORACLE_HOME
$ORA_CRS_HOME
/etc/init.d/init.cssd
/etc/init.d/init.crs
/etc/init.d/init.crsd
/etc/init.d/init.evmd
/var/tmp/.oracle/
/etc/oratab

Following files are optional and can be copied from other node

/oracle/.ssh
/oracle/.zshrc
/etc/oraInst.loc
/etc/oratab
/etc/fstab

1.Restore all the above mentioned files and setup ssh user equilance

2.Relink Software binaries of Oracle database home

Copy .zhrc file from the other node to oracle user home directory As oracle, run relink all

$cd $ORACLE_HOME/bin
 $./relink all

Ensure that it comes with clean exit. It is important to set ENV variables, so ensure .zshrc is executed

3.Run cluvfy to check whether all pre-requisite are met

cd $ORA_CRS_HOME/bin
/cluvfy stage -pre crsinst -n prod01,prod02

In case there are any errors then fix them before proceeding to next step
4.Execute root.sh as root from $ORA_CRS_HOME on node

[root@prod01 etc]# cd $ORA_CRS_HOME
[root@prod01 crs]# ./root.sh
WARNING: directory '/oracle/product' is not owned by root
Checking to see if Oracle CRS stack is already configured

Setting the permissions on OCR backup directory
Setting up NS directories
Oracle Cluster Registry configuration upgraded successfully
WARNING: directory '/oracle/product' is not owned by root
clscfg: EXISTING configuration version 3 detected.
clscfg: version 3 is 10G Release 2.
Successfully accumulated necessary OCR keys.
Using ports: CSS=49895 CRS=49896 EVMC=49898 and EVMR=49897.
node :   
node 1: prod01 prod01-i prod01
node 2: prod02 prod02-i prod02
clscfg: Arguments check out successfully.

NO KEYS WERE WRITTEN. Supply -force parameter to override.
-force is destructive and will destroy any previous cluster
configuration.
Oracle Cluster Registry for cluster has already been initialized
Startup will be queued to init within 30 seconds.
Adding daemons to inittab
Expecting the CRS daemons to be up within 600 seconds.
CSS is active on these nodes.
prod01
prod02
CSS is active on all nodes.
Waiting for the Oracle CRSD and EVMD to start
Waiting for the Oracle CRSD and EVMD to start
Oracle CRS stack installed and running under init(1M)
Running vipca(silent) for configuring nodeapps

Creating VIP application resource on (0) nodes.
Creating GSD application resource on (0) nodes.
Creating ONS application resource on (0) nodes.
Starting VIP application resource on (2) nodes...
Starting GSD application resource on (2) nodes...
Starting ONS application resource on (2) nodes...

You are done.