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

[Peter Santos]

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Adam,
thanks for the feedback.
I wanted to quickly show you my setup because I believe that
when I took down eth0, my connection hung even though my TAF policy is setup
properly.


eth0   - public ip of the machine
eth0:1 - vip managed by oracle. This is also what clients use to connect to.
         dns has entries called dbinsto# that point to the 3 vips on my cluster.

eth1   - private ip, used for cluster interconnect and o2cb service (cluster.conf)

my client tnsnames.ora
=======================================================================
ORACTAH =
  (DESCRIPTION =
    (LOAD_BALANCE = ON)
    (FAILOVER = ON)
    (ADDRESS = (PROTOCOL = TCP)(HOST = dbinsto1)(PORT = 1521))  <-- vip
    (ADDRESS = (PROTOCOL = TCP)(HOST = dbinsto2)(PORT = 1521))  <-- vip
    (ADDRESS = (PROTOCOL = TCP)(HOST = dbinsto3)(PORT = 1521))  <-- vip
    (CONNECT_DATA =
      (SERVER = SHARED)
      (SERVICE_NAME = ORACTAH)
          (FAILOVER_MODE =
            (TYPE = SELECT)
            (METHOD = BASIC)
            (RETRIES = 20)
            (DELAY = 5)
          )
    )
  )

Since the o2cb service operates via eth1 and there is no lost connectivity
to the shared device, o2cb should continue to work just fine, but
I was sure that the vip on this node did not get moved to another node.

When I repeated this same process on eth1, the o2cb service evicted this node
from the cluster and it was eventually rebooted.. not sure if it was
the o2cb service that caused it to reboot or oracle's CRS daemons.

I'll keep testing further.

thanks
- -peter



Adam Kenger wrote:
> 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:
> 
> 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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