[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"
>>switch="10.52.2.240"/>
>> </method>
>> <method name="2">
>> <device name="pwr02" port="1"
>>switch="10.52.2.241"/>
>> </method>
>> </fence>
>>
>
>I think you want something like this instead:
>
><fence>
> <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>
></fence>
>
>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.
>
>Dave
>
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>Linux-cluster at redhat.com
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>
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?
-J
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