rman备份出錯

Starting backup at 04-SEP-06
channel ch00: starting full datafile backupset
channel ch00: specifying datafile(s) in backupset
waiting for snapshot controlfile enqueue
waiting for snapshot controlfile enqueue
waiting for snapshot controlfile enqueue
waiting for snapshot controlfile enqueue
waiting for snapshot controlfile enqueue
cannot make a snapshot controlfile
released channel: ch00
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ch00 channel at 09/04/2006 02:02:31
ORA-00230: operation disallowed: snapshot controlfile enqueue unavailable

00230, 00000, "operation disallowed: snapshot controlfile enqueue unavailable"
// *Cause:  The attempted operation cannot be executed at this time because
//          another process currently holds the snapshot controlfile enqueue.
// *Action: Retry the operation after the concurrent operation that is holding
//          the snapshot controlfile enqueue terminates.

 

 

如果不通过rman，oracle是无法实现联机全备的，这也是oracle比较尴尬的事情，oracle通过rman实现了联机全备，最本质的原因就是引入了snapshot controlfile，因为scn时时刻刻是要被写入控制文件的，但是联机全备时又需要短暂的锁住控制文件（全备时要保证控制文件，数据文件scn是一致的啊），这样就产生了矛盾，于是在rman中就引入了snapshot controlfile，事实上在rman备份时用snapshot controlfile临时代替了controlfile，备份之后他们之间又重新同步了 [/B]