*** a/src/backend/access/transam/xlog.c
--- b/src/backend/access/transam/xlog.c
***************
*** 8200,8217 **** pg_start_backup(PG_FUNCTION_ARGS)
  				 errmsg("recovery is in progress"),
  				 errhint("WAL control functions cannot be executed during recovery.")));
  
! 	if (!XLogArchivingActive())
! 		ereport(ERROR,
! 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
! 				 errmsg("WAL archiving is not active"),
! 				 errhint("archive_mode must be enabled at server start.")));
! 
! 	if (!XLogArchiveCommandSet())
  		ereport(ERROR,
  				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
! 				 errmsg("WAL archiving is not active"),
! 				 errhint("archive_command must be defined before "
! 						 "online backups can be made safely.")));
  
  	backupidstr = text_to_cstring(backupid);
  
--- 8200,8210 ----
  				 errmsg("recovery is in progress"),
  				 errhint("WAL control functions cannot be executed during recovery.")));
  
! 	if (!XLogIsNeeded())
  		ereport(ERROR,
  				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
! 				 errmsg("WAL level not sufficient for making an online backup"),
! 				 errhint("wal_level must be set to 'archive' or 'hot_standby' at server start.")));
  
  	backupidstr = text_to_cstring(backupid);
  
***************
*** 8399,8409 **** pg_stop_backup(PG_FUNCTION_ARGS)
  				 errmsg("recovery is in progress"),
  				 errhint("WAL control functions cannot be executed during recovery.")));
  
! 	if (!XLogArchivingActive())
  		ereport(ERROR,
  				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
! 				 errmsg("WAL archiving is not active"),
! 				 errhint("archive_mode must be enabled at server start.")));
  
  	/*
  	 * OK to clear forcePageWrites
--- 8392,8402 ----
  				 errmsg("recovery is in progress"),
  				 errhint("WAL control functions cannot be executed during recovery.")));
  
! 	if (!XLogIsNeeded())
  		ereport(ERROR,
  				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
! 				 errmsg("WAL level not sufficient for making an online backup"),
! 				 errhint("wal_level must be set to 'archive' or 'hot_standby' at server start.")));
  
  	/*
  	 * OK to clear forcePageWrites
***************
*** 8511,8526 **** pg_stop_backup(PG_FUNCTION_ARGS)
  	CleanupBackupHistory();
  
  	/*
! 	 * Wait until both the last WAL file filled during backup and the history
! 	 * file have been archived.  We assume that the alphabetic sorting
! 	 * property of the WAL files ensures any earlier WAL files are safely
! 	 * archived as well.
  	 *
  	 * We wait forever, since archive_command is supposed to work and we
  	 * assume the admin wanted his backup to work completely. If you don't
  	 * wish to wait, you can set statement_timeout.  Also, some notices are
  	 * issued to clue in anyone who might be doing this interactively.
  	 */
  	XLByteToPrevSeg(stoppoint, _logId, _logSeg);
  	XLogFileName(lastxlogfilename, ThisTimeLineID, _logId, _logSeg);
  
--- 8504,8530 ----
  	CleanupBackupHistory();
  
  	/*
! 	 * If archiving is enabled, wait for all the required WAL files to be
! 	 * archived before returning. If archiving isn't enabled, the required
! 	 * WAL needs to be transported via streaming replication (hopefully
! 	 * with wal_keep_segments set high enough), or some more exotic
! 	 * mechanism like polling and copying files from pg_xlog with script.
! 	 * We have no control over those mechanisms, so it's up to the user to
! 	 * ensure that he gets all the required WAL.
! 	 *
! 	 * We wait until both the last WAL file filled during backup and the
! 	 * history file have been archived, and assume that the alphabetic
! 	 * sorting property of the WAL files ensures any earlier WAL files are
! 	 * safely archived as well.
  	 *
  	 * We wait forever, since archive_command is supposed to work and we
  	 * assume the admin wanted his backup to work completely. If you don't
  	 * wish to wait, you can set statement_timeout.  Also, some notices are
  	 * issued to clue in anyone who might be doing this interactively.
  	 */
+ 	if (XLogArchivingActive())
+ 	{
+ 		/* XXX: fix indentation before committing */
  	XLByteToPrevSeg(stoppoint, _logId, _logSeg);
  	XLogFileName(lastxlogfilename, ThisTimeLineID, _logId, _logSeg);
  
***************
*** 8559,8564 **** pg_stop_backup(PG_FUNCTION_ARGS)
--- 8563,8572 ----
  
  	ereport(NOTICE,
  			(errmsg("pg_stop_backup complete, all required WAL segments have been archived")));
+ 	}
+ 	else
+ 		ereport(NOTICE,
+ 				(errmsg("WAL archiving is not enabled, you must ensure that all required WAL segments are streamed or copied through other means to restore the backup")));
  
  	/*
  	 * We're done.  As a convenience, return the ending WAL location.