[Linux-cluster] Fencing Race Question

[Scott Becker]

In the FAQ, Fencing Questions
13. What's the right way to configure fencing when I have redundant 
power supplies?

I'm going to setup the second example.
My concern is about a race condition with the two devices:

|<device name="pwr01" option="off" switch="1" port="1"/>
<device name="pwr02" option="off" switch="1" port="1"/>|

If I had only one power switch, the first node to login successfully 
turns the other off (APC with one IP address). My concern is with two 
APCs, that whoever loses the race to login to APC #1 may win the race to 
login to APC #2 and then each will turn off only one of the other's 
power supplies.

Is the fencing execution script designed to 1) perform all necessary 
fencing device logins successfully then and only then 2) issue the 
poweroff commands? Thereby averting a potential race because the loser 
of the race for APC #1 will give up and hand over device #2.

    thanks
    newby
    scottb

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