diff -cr pgsql/src/backend/access/transam/xlog.c pgsql-arcstatdir/src/backend/access/transam/xlog.c
*** pgsql/src/backend/access/transam/xlog.c	Fri Oct 31 11:04:59 2008
--- pgsql-arcstatdir/src/backend/access/transam/xlog.c	Sat Nov  8 17:10:22 2008
***************
*** 438,444 ****
  				  XLogRecPtr *minRecoveryLoc);
  static void rm_redo_error_callback(void *arg);
  static int get_sync_bit(int method);
! 
  
  /*
   * Insert an XLOG record having the specified RMID and info bytes,
--- 438,444 ----
  				  XLogRecPtr *minRecoveryLoc);
  static void rm_redo_error_callback(void *arg);
  static int get_sync_bit(int method);
! static void ValidateXLOGDirectoryStructure(void);
  
  /*
   * Insert an XLOG record having the specified RMID and info bytes,
***************
*** 2825,2830 ****
--- 2825,2878 ----
  }
  
  /*
+  * The purpose of this procedure is to verify whether pg_xlog and
+  * pg_xlog/archive_status exist.  If the latter does not, it attempts
+  * to recreate it.  It is not the goal of this procedure to verify the
+  * contents of these directories, but to help in cases where someone
+  * has performed a cluster copy for PITR purposes but forgot to
+  * recreate archive_status in pg_xlog.
+  */
+ static void
+ ValidateXLOGDirectoryStructure(void)
+ {
+ 	char		path[MAXPGPATH];
+ 	struct stat	stat_buf;
+ 
+ 	/* Check for pg_xlog, if it doesn't exist, error out */
+ 	if (stat(XLOGDIR, &stat_buf) != 0 || !S_ISDIR(stat_buf.st_mode))
+ 	{
+ 		ereport(FATAL, 
+ 			(errmsg("required WAL directory \"%s\" does not exist",
+ 				XLOGDIR)));
+ 	}
+ 
+ 	/* Check for a pre-existing directory */
+ 	snprintf(path, MAXPGPATH, XLOGDIR "/archive_status");
+ 	if (stat(path, &stat_buf) == 0)
+ 	{
+ 		/* Check for weird cases where it exists but isn't a directory */
+ 		if (S_ISDIR(stat_buf.st_mode))
+ 			return; /* Directory structure looks good */
+ 		else
+ 			ereport(FATAL, 
+ 				(errmsg("required WAL directory \"%s\" does not exist", path),
+ 				 errhint("Expected \"%s\" to be a directory.", path)));
+ 	}
+ 	else
+ 	{
+ 		ereport(LOG,
+ 			(errmsg("recreating missing WAL directory \"%s\"", path)));
+ 
+ 		if (mkdir(path, 0700) < 0)
+ 		{
+ 			ereport(FATAL, 
+ 				(errmsg("could not create missing directory \"%s\"",
+ 					path)));
+ 		}
+ 	}
+ }
+ 
+ /*
   * Remove previous backup history files.  This also retries creation of
   * .ready files for any backup history files for which XLogArchiveNotify
   * failed earlier.
***************
*** 4879,4884 ****
--- 4927,4939 ----
  #endif
  
  	/*
+ 	 * Verify that pg_xlog and pg_xlog/archive_status exist.  In cases where
+ 	 * someone has performed a copy for PITR, these directories may have
+ 	 * been excluded and need to be re-created.
+ 	 */
+ 	ValidateXLOGDirectoryStructure();
+ 
+ 	/*
  	 * Initialize on the assumption we want to recover to the same timeline
  	 * that's active according to pg_control.
  	 */