Replication recovery after a prolonged shutdown slave Posgtgresql

t is possible that the slave will not receive data from the master after a prolonged shutdown of the slave 
Slave will return errors: 

  2011-04-15 15:22:49 UTC FATAL: could not receive data from WAL stream: FATAL: requested WAL segment 0000000100000002000000C5 has already been removed 

This is due to the fact that the master file is already fully recorded 0000000100000002000000C5 and moved it from the folder / var/lib/postgresql/9.0/main/pg_xlog in folder / var/lib/postgresql/9.0/main/archive. 

Required Actions: 

master 

  sudo-u postgres psql-c "SELECT pg_start_backup ('label', true)"
 cd / var/lib/postgresql/9.0/main
 tar cvzf ~ / archive.tgz archive
 sudo-u postgres psql-c "SELECT pg_stop_backup ()"
 scp-P 1022-r ~ / archive.tgz *   @   *
 sudo-u postgres psql-c "SELECT pg_current_xlog_location ()" 

slave 

  / Etc / init.d / postgresql stop
 tar xvzf ~ / archive.tgz-C / var/lib/postgresql/9.0/main
 chown-R postgres: postgres / var/lib/postgresql/9.0/main/archive
 / Etc / init.d / postgresql start
 sudo-u postgres psql-c "SELECT pg_last_xlog_replay_location ()"