[Linux-cluster] Arbitrary heuristics
Scott Becker
scottb at bxwa.com
Tue Nov 20 22:06:59 UTC 2007
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?
thanks
scottb
Lon Hohberger wrote:
> Correct, it needs a shared volume. Without one, you should use cman
> two_node mode.
>
>
>
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