[Ocfs2-users] 2 node OCFS2 clusters

[Luis Freitas]

Joel,

   Sorry but I don't agree on this.

   For CRS there is no need for a dedicated switch, only a need for using switches instead of cross cables. Although it is not recommended you can use the same switch for the public and private networks, using different vlans. The network status can be checked by the link status, that is what CRS does, and also by pinging the router. This information could be used as part of the heuristics to decide which node should survive. Of course it doesn't cover all network topologies, but it is sure better than node 0 always survive when network is down.

   I see this as a problem in a RAC implementation, since there are two different cluster stacks running (O2CB and CRS), they are not integrated and take decisions with a different heuristic. For me it would make more sense if they were integrated and one of the cluster stacks was in control, in the same way that happens when you use RAC with Veritas/HP ServiceGuard/Sun Cluster Suite, or OCFS2 with heartbeat2, for example.

Best Regards,
Luis Freitas

--- On Mon, 11/16/09, Joel Becker <Joel.Becker at oracle.com> wrote:

> From: Joel Becker <Joel.Becker at oracle.com>
> Subject: Re: [Ocfs2-users] 2 node OCFS2 clusters
> To: "Luis Freitas" <lfreitas34 at yahoo.com>
> Cc: "Srinivas Eeda" <srinivas.eeda at oracle.com>, ocfs2-users at oss.oracle.com
> Date: Monday, November 16, 2009, 5:38 PM
> On Mon, Nov 16, 2009 at 08:55:38AM
> -0800, Luis Freitas wrote:
> >   If this is true then I would sugest
> OCFS2 is not taking the best decision in this scenario.
> 
>     It's doing the best it can.  See,
> each node knows the other is
> alive because of the disk heartbeat.  Thus they know
> the error is
> network related.  But with only two nodes, there is no
> way to determine
> who has the better network.
> 
> >   The node that still has network
> connectivity should survive instead of the lowest node
> number. Oracle CRS has heuristics to detect if the network
> is down and in this scenario the node that lost network
> conectivy is evicted. That is why it is required to use a
> switch between the two nodes, instead of a cross cable. 
> 
>     ocfs2 is a general purpose filesystem
> that allows a myriad of
> network configurations.  It has never required a
> dedicated network
> switch, nor will it, so relying on that isn't possible.
> 
> Joel
> 
> -- 
> 
> "The whole problem with the world is that fools and
> fanatics are always
>  so certain of themselves, and wiser people so full of
> doubts."
>     - Bertrand Russell
> 
> Joel Becker
> Principal Software Developer
> Oracle
> E-mail: joel.becker at oracle.com
> Phone: (650) 506-8127
>