在Oracle10.2.0.3 RAC的测试中，发现如果修改某个节点的系统时间超过1.5秒，那么这个节点会被自动重新启动。

好狠的处理方式 ......

详细机制参见Internal Only的Metalink Note 308051.1。

The OPROCD executable sets a signal handler for the SIGALRM handler and sets the interval timer based on the to-millisec parameter provided.  The alarm handler gets the current time and checks it against the time that the alarm handler was last entered.  If the difference exceeds (to-millisec + margin-millisec), it will fail; the production version will cause a node reboot.

尝试修改/etc/init.cssd中关于OPROCD的配置，将DISABLE_OPROCD设置为TRUE，然后重新启动系统，在系统进程中已经不存在oprocd进程，但是居然修改完系统时间以后，机器仍然被重新启动了。

文档中另外的描述提到，如果OPROCD是在non fatal mode状态下启动的，那么将只会写一段log而不去重新启动机器，并且在Note:265769.1中也描述了如何修改为non fatal mode，但是我没有去尝试。

In fatal mode, OPROCD will reboot the node if it detects excessive wait. In Non Fatal mode, it will write an error message out to the file <hostname>.oprocd.log in one of the following directories.

最后尝试的结果是将整个cssd进程disable掉，这样可以避免因为修改系统时间而引起机器重启。

这段时间发现Oracle10g的CRS确实有些霸道，上次的测试中拔掉Private IP网卡上的网线，操作系统会重新启动，这次居然修改系统时间也会导致系统重启，真当这些机器是Windows了？UNIX Server中重启一次机器多大的事儿啊，CRS搞的跟吃饭一样随意，动不动reboot。

下面的这段资料描述了Oracle CRS的三个进程会在哪些状态下重新启动机器。

Oracle clusterware has the following three daemons which may be responsible for panicing the node. It is possible that some other external entity may have rebooted the node. In the context of this discussion, we will assume that the reboot/panic was done by an Oracle clusterware daemon.

* Oprocd  - Cluster fencing module
* Cssd - Cluster sychronization module which manages node membership
* Oclsomon - Cssd monitor which will monitor for cssd hangs

OPROCD This is a daemon that only gets activated when there is no vendor clusterware present on the OS. This daemon is also not activated to run on Windows/Linux.  This daemon runs a tight loop and if it is not scheduled for 1.5 seconds, will reboot the node.
CSSD This daemon pings the other members of the cluster over the private network and Voting disk. If this does not get a response for Misscount seconds and Disktimeout seconds respectively, it will reboot the node.
Oclsomon This daemon monitors the CSSD to ensure that CSSD is scheduled by the OS, if it detects any problems it will reboot the node.

需要找到方法去禁用这些reboot的特性，reboot了你又不能解决问题，瞎操什么心嘛。

1201会不会自动重启呢

哈哈贴internal only的东东，胆子大 thx

每个节点的时间相差多了，节点会down掉，重启倒是没碰到过

经历同楼上的样

正准备做一个10G的RAC项目，怕怕，也太狠了

QUOTE:

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最初由 Kamus 发布
在Oracle10.2.0.3 RAC的测试中，发现如果修改某个节点的系统时间超过1.5秒，那么这个节点会被自动重新启动。

好狠的处理方式 ......

详细机制参见Internal Only的Metalink Note 308051.1。

The OPROCD executable sets a signal handler for the SIGALRM handler and sets the interval timer based on the to-millisec parameter provided.  The alarm handler gets the current time and checks it against the time that the alarm handler was last entered.  If the difference exceeds (to-millisec + margin-millisec), it will fail; the production version will cause a node reboot.

尝试修改/etc/init.cssd中关于OPROCD的配置，将DISABLE_OPROCD设置为TRUE，然后重新启动系统，在系统进程中已经不存在oprocd进程，但是居然修改完系统时间以后，机器仍然被重新启动了。

文档中另外的描述提到，如果OPROCD是在non fatal mode状态下启动的，那么将只会写一段log而不去重新启动机器，并且在Note:265769.1中也描述了如何修改为non fatal mode，但是我没有去尝试。

In fatal mode, OPROCD will reboot the node if it detects excessive wait. In Non Fatal mode, it will write an error message out to the file <hostname>.oprocd.log in one of the following directories.

最后尝试的结果是将整个cssd进程disable掉，这样可以避免因为修改系统时间而引起机器重启。

这段时间发现Oracle10g的CRS确实有些霸道，上次的测试中拔掉Private IP网卡上的网线，操作系统会重新启动，这次居然修改系统时间也会导致系统重启，真当这些机器是Windows了？UNIX Server中重启一次机器多大的事儿啊，CRS搞的跟吃饭一样随意，动不动reboot。

下面的这段资料描述了Oracle CRS的三个进程会在哪些状态下重新启动机器。

Oracle clusterware has the following three daemons which may be responsible for panicing the node. It is possible that some other external entity may have rebooted the node. In the context of this discussion, we will assume that the reboot/panic was done by an Oracle clusterware daemon.

* Oprocd  - Cluster fencing module
* Cssd - Cluster sychronization module which manages node membership
* Oclsomon - Cssd monitor which will monitor for cssd hangs

OPROCD This is a daemon that only gets activated when there is no vendor clusterware present on the OS. This daemon is also not activated to run on Windows/Linux.  This daemon runs a tight loop and if it is not scheduled for 1.5 seconds, will reboot the node.
CSSD This daemon pings the other members of the cluster over the private network and Voting disk. If this does not get a response for Misscount seconds and Disktimeout seconds respectively, it will reboot the node.
Oclsomon This daemon monitors the CSSD to ensure that CSSD is scheduled by the OS, if it detects any problems it will reboot the node.

需要找到方法去禁用这些reboot的特性，reboot了你又不能解决问题，瞎操什么心嘛。

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not sure you are joking or now. :-) . the reboot is one of the way to avoid corruption issue such as those in split brain and it is the one choosed by oracle.  reboot means better safe then sorry.

and since oracle runs on user mode only . it may not be scheduled. so that is why so complex.

once reboot, the reboot node need to join the cluster again following the normal process. It can succeed or it can fail . either way , it is very clear and no unknown situation. therefore , avoid the prospect of having any corruption.

that is what "fencing" about .

整的还挺详细，貌似不是愚人节新闻，哈哈