Problem on cluster initialization

Hi all!

We've a problem...

A made a tar backup copy of /var/lib/pgsql, but now (I'm still with Postgre 
7.2 on a RedHat 7.3) restoring the data and launching the daemon i receive:

postmaster successfully started
bash-2.05$ FATAL 2:  The database cluster was initialized with 
CATALOG_VERSION_NO 200101061,       but the backend was compiled with CATALOG_VERSION_NO 200201121.       It looks like
youneed to initdb.
 

Can someone explain to me how to rebuild it? :-)

No matter if i've to recompile the sources... i MUST recover the DB.

Thank you for your help!

Silvio Mazzaro