[Linux-cluster] 2-node tie-breaking

[Gordan Bobic]

Jakub Suchy wrote:
>>> Well, here's a cheap 'out' ;)
>>> Ebay item # 250213910258
>>> 8 port WTI NPS for $70 + $15 s/h.
>> Indeed, that would be tempting if it wasn't on the wrong side of the 
>> atlantic. A more local search for similar things doesn't seem to come up 
>> with anything. :-(
> 
> Another "cheap" power switch may be:
> 
> http://www.hw-group.com/products/ip_watchdog/index_lite_en.html
> 
> Made by a Czech Republic (= right side of the atlantic :) company,
> allows power switching of two servers. Requires you to write a fencing
> script and connect power output cables from this device to power
> switches in the servers. Again - never tried, but it's around 3188 Czech
> crowns, which is approx. $187.

Yeah, but that's not that far off a couple of cheap UPS-es with basic 
serial interfaces. I could cross-connect them so that Server-A is 
powered off UPS-A, and is controlling UPS-B via serial/USB. Same in 
reverse on the other machine.

That way Server-A can power off Server-B and vice versa.

The upshot being that at least that way I have UPS capability.

But it'd still be nice to have a software only "might work most of the 
time" solution. It should work at least in the cases where preservation 
of the GFS is the main concern, as all the surviving nodes should be 
able to firewall off the node they think has died. Resource fail-over 
might still be an issue, but at least the cluster itself would stay safe 
and functional.

Gordan