sudo /etc/init.d/postgresql start
 * Starting PostgreSQL 9.1 database server                                                   * The PostgreSQL server failed to start. Please check the log output:
2012-08-17 16:02:33 CEST FATAL:  could not load root certificate file "root.crt": no SSL error reported

ls -la
total 92
drwx------ 13 postgres postgres  4096 Aug 16 14:36 .
drwxr-xr-x  3 root     root      4096 Aug 16 13:57 ..
drwx------  5 postgres postgres  4096 Aug 16 14:00 base
drwx------  2 postgres postgres  4096 Aug 16 14:36 global
drwx------  2 postgres postgres  4096 Aug 16 14:00 pg_clog
-rw-------  1 postgres postgres  4476 Aug 16 14:00 pg_hba.conf
-rw-------  1 postgres postgres  1636 Aug 16 14:00 pg_ident.conf
drwx------  4 postgres postgres  4096 Aug 16 14:00 pg_multixact
drwx------  2 postgres postgres  4096 Aug 16 14:35 pg_notify
drwx------  2 postgres postgres  4096 Aug 16 14:00 pg_serial
drwx------  2 postgres postgres  4096 Aug 16 14:36 pg_stat_tmp
drwx------  2 postgres postgres  4096 Aug 16 14:00 pg_subtrans
drwx------  2 postgres postgres  4096 Aug 16 14:00 pg_tblspc
drwx------  2 postgres postgres  4096 Aug 16 14:00 pg_twophase
-rw-------  1 postgres postgres     4 Aug 16 14:00 PG_VERSION
drwx------  3 postgres postgres  4096 Aug 16 14:00 pg_xlog
-rw-------  1 postgres postgres 19169 Aug 16 14:00 postgresql.conf
-rw-------  1 postgres postgres   126 Aug 16 14:35 postmaster.opts
lrwxrwxrwx  1 postgres postgres    31 Aug 16 14:13 root.crt -> /etc/postgresql-common/root.crt
lrwxrwxrwx  1 postgres postgres    36 Aug 16 14:13 server.crt -> /etc/ssl/certs/ssl-cert-snakeoil.pem
lrwxrwxrwx  1 postgres postgres    38 Aug 16 14:13 server.key -> /etc/ssl/private/ssl-cert-snakeoil.key

sudo -u postgres cat /etc/postgresql-common/root.crt

This is a dummy root certificate file for PostgreSQL. To enable client side
authentication, add some certificates to it. Client certificates must be signed
with any certificate in this file to be accepted.

A reasonable choice is to just symlink this file to
/etc/ssl/certs/ssl-cert-snakeoil.pem; in this case, client certificates need to
be signed by the postgresql server certificate, which might be desirable in
many cases. See

  file:///usr/share/doc/postgresql-doc-8.3/html/ssl-tcp.html

for details (in package postgresql-doc-8.3).

ln -s /etc/ssl/certs/ssl-cert-snakeoil.pem root.crt