[Linux-cluster] fenced(8) not fencing through all fenceing devices

Jim Parsons jparsons at redhat.com
Thu Feb 1 19:59:24 UTC 2007

David Teigland wrote:

>On Thu, Feb 01, 2007 at 06:50:36PM +0100, Miroslav Zubcic wrote:
>>        <clusternodes>
>>                <clusternode name="tan9f1" votes="1">
>>                        <fence>
>>                                <method name="1">
>>                                        <device name="pwr01" port="1"
>>                                </method>
>>                                <method name="2">
>>                                        <device name="pwr02" port="1"
>>                                </method>
>>                        </fence>
>I think you want something like this instead:
>	<method name="1">
>		<device name="pwr01" option="off" port="1" ../>
>		<device name="pwr02" option="off" port="1" ../>
>		<device name="pwr01" option="on" port="1" ../>
>		<device name="pwr02" option="on" port="1" ../>
>	</method>
>There are two problems with your config:
>1. You have both devices in separate methods.  A second method is only
>tried if the first fails.  
>2. You're using the default "reboot" option which isn't reliable with dual
>power supplies.  The first port may come back on before the second is
>turned off.  So, you need to turn both ports off (ensuring the power is
>really off) before turning either back on.
>You may still have a minor problem, though, because in the two-node
>cluster mode, a cluster partition will result in both nodes trying to
>fence each other in parallel.  With a single power supply this works fine
>because one node will always be turned off before it can turn off the
>other.  But, with dual power supplies you can get both nodes turning off
>one power port on the other, although only one of the nodes should succeed
>in turning off the second power port.  i.e. the winner of the fencing race
>may end up with one of its power ports turned off.  Whether this is a big
>problem, I don't know.
>Linux-cluster mailing list
>Linux-cluster at redhat.com
Did you use system-config-cluster to generate this config file? It sets 
up redundant power supply fencing for you. What are the fencedevices 
being used here?


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