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Re: [Linux-cluster] Arbitrary heuristics

I've been pondering what I'm actually looking for.

Each of my nodes has a public and a private NIC. Public is for serving web pages, private is for fencing. I was desperately trying to get fencing to work over the public network but I was faced with reimplementing a complicated fence agent in C in order to use ssh (supported ok by my power switches but difficult to add to the python fence agent).

My remaining issue is that if I lose one of my public NICs, I must ensure that the ensuing fencing race is won by the good node and not the bad node which thinks it's good. Not solved by quorum because I must also make it work, 'last man standing' (starting with 3 nodes).

So pondering, I realized that I don't really need to monitor the ability to reach the gateway. What I need is for a public comm error to create an event, hence I use the public nic for cluster comms. Then do something so that the bad node doesn't fence the good nodes.

So assuming only one real failure at a time, I'm thinking of making the first step in the fencing method a check for pinging the gateway. That way when a node wants to fence, it will only be able to if it's public NIC is working, even though it's using the private nic for the rest of the fencing.

Am I off?


Lon Hohberger wrote:
Correct, it needs a shared volume.  Without one, you should use cman
two_node mode.

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