[Ocfs2-users] re: how should ocfs2 react to nic hardware issue

[Adam Kenger]

Peter - depending on how you have your RAC cluster setup, the hang on  
the front end is not that unexpected.  It depends on how the user was  
connected and how the TAF policy was set up.  Eth0 is your public  
interface I assume.  Was the user connecting to the IP on that  
interface or to the VIP set up by RAC?  When you down eth0 the VIP on  
that interface should get pushed over onto one of the other 2 nodes  
in the cluster.  If you're connecting to a "service" versus an actual  
"instance" there should be no hang on the front end.  If you're  
actually connected directly to the instance on the node, then you'll  
be out of luck if you disconnect that instance.  As an example, this  
is what the corresponding tnsnames.ora file looks like :

MYDBSERVICE =
   (DESCRIPTION =
     (ADDRESS_LIST =
       (ADDRESS = (PROTOCOL = TCP)(HOST = node1-vip)(PORT = 1521))
       (ADDRESS = (PROTOCOL = TCP)(HOST = node2-vip)(PORT = 1521))
       (ADDRESS = (PROTOCOL = TCP)(HOST = node3-vip)(PORT = 1521))
     )
     (CONNECT_DATA =
       (SERVICE_NAME = mydbservice.db.mydomain.com)
     )
   )

MYDB1 =
   (DESCRIPTION =
     (ADDRESS = (PROTOCOL = TCP)(HOST = node1-vip)(PORT = 15
21))
     (CONNECT_DATA =
       (SERVER = DEDICATED)
       (SERVICE_NAME = mydb.db.mydomain.com)
       (INSTANCE_NAME = mydb1)
     )
   )

If you connected to the service "MYDBSERVICE" you could survive the  
failure of any given node.  You'd seamlessly fail-over onto one of  
the other nodes.  If you connect directly to the "MYDB1" instance,  
you'll be out of luck if you drop the connection to it.

As far as o2cb goes, you are right I believe.  Eventually, it will be  
determined that the node is no longer heartbeating and will either  
panic or reboot.

For your testing, just be careful you're not confusing the OCFS2  
layer with the Oracle CRS/RAC layers.

Comments welcome....

Hope that helps

Adam




On Nov 30, 2006, at 3:30 PM, Peter Santos wrote:

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> guys,
> 	I'm trying to test how my 10gR2 oracle cluster (3 nodes) on SuSe  
> reacts to a network card hardware failure.
> 	I have eth0 and eth1 as my network cards, I took down eth0 (ifdown  
> eth0) to see what would happen and
> 	I didn't get any reaction from the o2cb service. This is probably  
> the correct behavior since my
>  	/etc/ocfs2/cluster.conf uses eth1 as the connection channel?
>
> 	If I take down eth1 I suspect o2cb will eventually reboot the  
> machine right? I'm not using any bonding.
>
> 	My concern is that when I took down eth0, I had a user logged into  
> the instance and everything just "hung" for
> 	that user, until I manually took down the instance with  
> "SRVCTL"... then the user connection failed over to
> 	a working instance.
>
> 	Anyway, just trying to get some general knowledge of the behavior  
> of o2cb in order to understand
> 	my testing.
>
> - -peter
>
>
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