The master and slave servers are set up as per the tutorial https://www.digitalocean.com/community/tutorials/how-to-set-up-master-slave-replication-on-postgresql-on-an-ubuntu-12-04-vps and both servers are Ubuntu 12.04 x64 and are running PostgreSQL 9.1

below are the commands I am running and the errors I am getting, any help will be appreciated.

MASTER SERVER

$ sudo su - postgres
$ psql -c "select pg_start_backup('initial_backup');"
$ rsync -cva --inplace --exclude=*pg_xlog* /var/lib/postgresql/9.1/main/ MAS.TER.SER.VER:/var/lib/postgresql/9.1/main/
$ psql -c "select pg_stop_backup();"

$ psql -c "select pg_stop_backup();"
NOTICE:  pg_stop_backup cleanup done, waiting for required WAL segments to be archived
WARNING:  pg_stop_backup still waiting for all required WAL segments to be archived (60 seconds elapsed)
HINT:  Check that your archive_command is executing properly.  pg_stop_backup can be canceled safely, but the database backup will not be usable without all the WAL segments.
WARNING:  pg_stop_backup still waiting for all required WAL segments to be archived (120 seconds elapsed)
HINT:  Check that your archive_command is executing properly.  pg_stop_backup can be canceled safely, but the database backup will not be usable without all the WAL segments.
^CCancel request sent
ERROR:  canceling statement due to user request

SLAVE SERVER

After running the above on the master I then set up the recovery.conf as per the tutorial and attempt to start the slave server.

$ sudo su - postgres
$ nano /etc/postgresql/9.1/main/recovery.conf

Edit as per tutorial

$ service postgresql start
 * Starting PostgreSQL 9.1 database server                                                                                                                            * Removed stale pid file.
The PostgreSQL server failed to start. Please check the log output:
2014-07-21 22:31:12 BST LOG:  database system was interrupted; last known up at 2014-07-21 22:21:43 BST
2014-07-21 22:31:12 BST LOG:  could not open file "pg_xlog/000000010000000000000018" (log file 0, segment 24): No such file or directory
2014-07-21 22:31:12 BST LOG:  invalid checkpoint record
2014-07-21 22:31:12 BST FATAL:  could not locate required checkpoint record
2014-07-21 22:31:12 BST HINT:  If you are not restoring from a backup, try removing the file "/var/lib/postgresql/9.1/main/backup_label".
2014-07-21 22:31:12 BST LOG:  startup process (PID 8274) exited with exit code 1
2014-07-21 22:31:12 BST LOG:  aborting startup due to startup process failure