DG的备库没一分钟会报一个错误，大家帮我分析一下，谢谢
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:15:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:16:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:17:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:18:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed

DG的备库没一分钟会报一个错误，大家帮我分析一下，谢谢
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:15:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:16:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:17:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed
Fri Apr 25 05:18:19 2014
PING[ARC1]: Heartbeat failed to connect to standby 'rz2'. Error is 16009.
Crash Recovery Foreground: All standby destinations have failed