How to set Database Timezone in Oracle RAC

In order to set the database timezone for Oracle 11g RAC, perform the following:
$ srvctl setenv database -d <dbname> -t TZ=<the TZ you want>
$ gsdctl stop
$ gsdctl start
For example:
To set the db timezone of RAC database called dbtst to Australia/Sydney, perform the following:
$ srvctl setenv database -d dbtst -t TZ=Australia/Sydney
$ gsdctl stop
$ gsdctl start
To check the timezone setting, issue the following:
$ srvctl getenv database -d dbtst