I have followed aforementioned steps in order to get multisite subdomain install
1)Install drupal in web server directory i.e. /var/www/html/drupal (this is the main drupal install). The server name is abc.com
2) For multisite subdirectory install I have created site1 folder under /var/www/html/drupal/sites/abc.com.drupal.sites1
Copied the default.settings.php into /var/www/html/drupal/sites/drupal.sites1/settings.php
modified db_url to $db_url='pgsql://my_db_username:my_db_password@localhost/my_site1_dbname';
modified base_url to $base_url="http://abc.com/drupal/site1"
created a symlink in drupal installation dir i.e. ln -s /var/www/html/drupal /var/www/html/drupal/site1
Also I have Options +FollowSymLinks within the .htacess file of drupal installation as well as
<Directory /var/www/html/drupal> Options FollowSymLinks </Directory> in my httpd.conf file
However in order to resume installation when I point my browser to http://abd.com/drupal/site1
I get following error message in my error log files "Symbolic link not allowed or link target not accessible"
I have overhauled most of the drupal forums but no luck so far. Help would be appreciated.