Changing CRS/Database timezone in 11.2.0.2 post install

Recently we need to modify our prod RAC cluster timezone from CST to EST. This is 8 node cluster hence we got to make sure the changes are reflected on all nodes properly. 

First thing is to make sure your OS is reflecting the correct TZ as per your need. Usually this is been taken care by SAs. 
So one needs to get confirmation from SAs that OS is ready with new Time zone values. Post that DBAs need to perform following changes on Grid 

The timezone info in Grid home is stored in the following file ....
$GRID_HOME/crs/install/s_config_(hostname).txt

#cd /u01/app/grid/11.2.0.2/crs/install

-- file which contains the values is following, where xxxxx is my host name.

# cat s_crsconfig_xxxxxxxx.txt
TZ=UTC
NLS_LANG=AMERICAN_AMERICA.AL32UTF8
TNS_ADMIN=
ORACLE_BASE=

To resolve the issue we need to change TZ to EST on all nodes and restart clusterware. So entry would be like
===
From TZ=UTC ==> TZ=America/New_York

On Restarting clusteware , database and clusteware starts with correct timezone.


Remember - The time zone of the system is defined by the contents of /etc/localtime