[Linux-cluster] What if the fence device doesn't work?

[Eric Kerin]

Janne Peltonen wrote:
> On Tue, Nov 21, 2006 at 09:20:20AM -0500, Eric Kerin wrote:
>   
>> Janne Peltonen wrote:
>>     
>> And here's an example block from the cluster.conf file first it tries 
>> ilo (HP Lights Out), and if that fails, apc (APC Network power 
>> controller) (the ILO sections is probably not correct, I just thew it in 
>> there as an example of how you'd setup the method tags):
>>                        <fence>
>>                                <method name="ilo">
>>                                        <device name="server1-ilo" 
>> option="off"/>
>>                                        <device name="server1-ilo" 
>> option="on"/>
>>                                </method>
>>                                <method name="apc">
>>                                        <device name="APC01a" port="1" 
>> option="off"/>
>>                                        <device name="APC01b" port="1" 
>> option="off"/>
>>                                        <device name="APC01a" port="1" 
>> option="on"/>
>>                                        <device name="APC01b" port="1" 
>> option="on"/>
>>                                </method>
>>
>>                        </fence>
>>     
>
> Ok, I tried a similar config and it works fine. Thanks again. One
> obstacle less on our way to a xen-csgfs-clustered imap server :)
>
> One thing, though: if the APC controller in the above config fails, it's
> still a SPOF. Or is there still something I'm missing?-)
>
>   
Well, first it tries ilo.  If that fails, it uses the APC.  If that 
fails, then we have a multipoint failure, and obviously protecting 
against multipoint failure costs a lot more than protecting against a 
single point failure...

Thanks,
Eric Kerin
eric at bootseg.com