Step1:

List of Tablespace:

   Name     |  Owner   |             Location             
-------------+----------+----------------------------------
 acct_tbsp   | postgres | /opt/PostgreSQL/tbspc
 pg_default  | postgres | 
 pg_global   | postgres | 
 test_tblspc | postgres | /opt/PostgresPlus/9.2AS/tblspc_1


Step2:

postgres=# select pg_start_backup('online_backup');
 pg_start_backup 
-----------------
 0/15000028
(1 row)


Step3:
Take backup of each tablespace location
cd /opt/PostgresPlus/9.2AS
tar -xzvf tblspc_1.tar.gz tblspc_1

cd /opt/PostgreSQL
tar -xzvf tbspc.tar.gz tbspc


Step4:
Take Backup of data directory.

cd $PGDATA/..
tar -czvf data.tar.gz data


Step5:
postgres=# select pg_stop_backup()
postgres-# ;
NOTICE:  pg_stop_backup complete, all required WAL segments have been archived
 pg_stop_backup 
----------------
 0/15015228
(1 row)


Step6: Create test tables on both the tablespaces

postgres=# create table after_online_backup_at_acct_tbsp(col1 int) tablespace acct_tbsp;
CREATE TABLE

postgres=# create table after_online_backup_at_test_tblspc(col1 int) tablespace test_tblspc;
CREATE TABLE



Step7:
Remove the directory for tablespace in another window:

rm -rf /opt/PostgreSQL/tbspc


Step8: Try to access the table which points to removed file

postgres=# select * from after_online_backup_at_tblspc1;
ERROR:  relation "after_online_backup_at_tblspc1" does not exist
LINE 1: select * from after_online_backup_at_tblspc1;


Step9: Restart the server- pg_ctl restart -m fast 

Check logs: Error noted-

2014-05-20 20:57:24 SGT LOG:  database system was shut down at 2014-05-20 20:57:23 SGT
2014-05-20 20:57:24 SGT LOG:  could not open tablespace directory "pg_tblspc/41918/PG_9.3_201306121": No such file or directory
2014-05-20 20:57:24 SGT LOG:  autovacuum launcher started
2014-05-20 20:57:24 SGT LOG:  database system is ready to accept connections


List the tablesapces:
postgres=# \db
                    List of tablespaces
    Name     |  Owner   |             Location             
-------------+----------+----------------------------------
 acct_tbsp   | postgres | /opt/PostgreSQL/tbspc
 pg_default  | postgres | 
 pg_global   | postgres | 
 test_tblspc | postgres | /opt/PostgresPlus/9.2AS/tblspc_1


Step10: Prepare for a recovery:
Stop the server
pg_ctl stop -m fast


go to data directory
cd $PGDATA
create recovery.conf with below content

restore_command = 'cp /opt/PostgresPlus/arch_dir/%f %p'


restore the tablespace backup:
cd /opt/PostgreSQL
tar -xzvf tbspc.tar.gz 


start PostgreSQL 
pg_ctl start