* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.85 2001/12/28 18:16:41 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.86 2002/01/14 17:55:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
WriteRqst.Write = WriteRqstPtr;
WriteRqst.Flush = record;
XLogWrite(WriteRqst);
- if (XLByteLT(LogwrtResult.Flush, record))
- elog(STOP, "XLogFlush: request %X/%X is not satisfied --- flushed only to %X/%X",
- record.xlogid, record.xrecoff,
- LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff);
}
LWLockRelease(WALWriteLock);
}
END_CRIT_SECTION();
+
+ /*
+ * If we still haven't flushed to the request point then we have a
+ * problem; most likely, the requested flush point is past end of XLOG.
+ * This has been seen to occur when a disk page has a corrupted LSN.
+ *
+ * Formerly we treated this as a STOP condition, but that hurts the
+ * system's robustness rather than helping it: we do not want to take
+ * down the whole system due to corruption on one data page. In
+ * particular, if the bad page is encountered again during recovery then
+ * we would be unable to restart the database at all! (This scenario
+ * has actually happened in the field several times with 7.1 releases.
+ * Note that we cannot get here while InRedo is true, but if the bad
+ * page is brought in and marked dirty during recovery then
+ * CreateCheckpoint will try to flush it at the end of recovery.)
+ *
+ * The current approach is to ERROR under normal conditions, but only
+ * NOTICE during recovery, so that the system can be brought up even if
+ * there's a corrupt LSN. Note that for calls from xact.c, the ERROR
+ * will be promoted to STOP since xact.c calls this routine inside a
+ * critical section. However, calls from bufmgr.c are not within
+ * critical sections and so we will not force a restart for a bad LSN
+ * on a data page.
+ */
+ if (XLByteLT(LogwrtResult.Flush, record))
+ elog(InRecovery ? NOTICE : ERROR,
+ "XLogFlush: request %X/%X is not satisfied --- flushed only to %X/%X",
+ record.xlogid, record.xrecoff,
+ LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff);
}
/*