I have RHEL5.3 that is with the Platform Cluster Manger PCM installation. on master node. Unfortunately some files were deleted from the /var directory and then the postgresql service couldn't start. I have deleted, rm -rf /var/lib/pgsql/data and started the service again now the service is running but I cannot run some administrative commands including cluster tasks (which are very important).

for example

[root@pmd02 ~]# addhost
KusuDB: Operational Error occurred when connecting to the DB
       Most likely cause: insufficient permissions for user=nobody
FATAL:  Ident authentication failed for user "nobody"

ERROR:  Database query failed!  Make sure the database is available

If you delete your database, your database probably isn't going to work anymore.