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关于 rac vip fail back

原创 Oracle 作者:dingzihan 时间:2014-03-21 14:54:38 0 删除 编辑
今天在测试rac 11g时发现vip不能自己飘过来,于是查了下些资料,做如下整理:
10.2.0.1 / 10.2.0.2: There is not permanent network monitoring, so it is not possible knowing when the public interface is back again, therefore we need to do a manual fail back 
             
crs_relocate 

10.2.0.3: The VIP automatically fails back when the network is up again, however the implementation wasn't totally fine and there are some side-effects introduced. 
More in detail, it was the instance ( every 10 minutes ) the one who tries to move the  VIP  back to the preferred node (original node) doing this:

Stop the VIP
Start up the VIP on the original node

So in case the network wasn't  fully available this operation will fail causing a new fail-over
During this time there's no service and one instance should exists at least in the node to  perform the check

10.2.0.4: There's no VIP automatic fail back anymore, however it is possible to emulate the 10.2.0.3 behavior uncommenting the line 

ORA_RACG_VIP_FAILBACK=1 && export ORA_RACG_VIP_FAILBACK
Location: racgwrap script @ ORACLE_HOME
11gR2 Starting with 11.2, the failover is made trough the monitoring of a newly introduced network resource.
You may have noticed this new resource:

crsctl status resource -t
     ora.net1.network
     ONLINE ONLINE rac1
     ONLINE ONLINE rac2

This resource monitors the network constantly, so its not the instance anymore
In case the network fails, there's a new feature called "offline resource monitoring", so it keeps pinging every 60 seconds ( default ) the network to check if its back again

crsctl stat type ora.network.type -p
ATTRIBUTE=OFFLINE_CHECK_INTERVAL
DEFAULT_VALUE=60
Finally, it is also possible to disable this feature by setting the OFFLINE_CHECK_INTERVAL in the network resource to zero by doing this

crsctl modify type ora.network.type -attr "ATTRIBUTE=OFFLINE_CHECK_INTERVAL
,TYPE='int',DEFAULT_VALUE=0"
Please note that is not supported to edit the ora.* resources 

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