[ClusterLabs] About fencing stonith

[Klaus Wenninger]

On 09/06/2018 10:47 PM, Digimer wrote:
> On 2018-09-06 04:33 PM, Marcos Renato da Silva Junior wrote:
>> Hi,
>>
>> I created a testing environment based on Raspberry Pi (attached
>> diagram), in my tests it has worked well, but I did not implement
>> anything about fencing and stonith, what is the need and how to implement?
>>
>> Thanks,
>>
>> Marcos.
> It depends on the hardware you have available. In your case, RPi has no
> IPMI or similar feature, so you'll need something external, like a
> switched PDU. I like the APC AP7900 (or your countries variant), which
> you can often get used for a decent price if this isn't a production system.
>
> http://www.apc.com/shop/us/en/products/Rack-PDU-Switched-1U-15A-100-120V-85-15/P-AP7900
>
>
For a test-environment switching mains might be an overkill.
And it makes the nice and tiny test-environment a lot less
nice and tiny ;-)
Anyway the scenario made me google a little bit.
e.g.: https://www.yepkit.com/products/ykush
is what I stumbled over.
Add a RPi to it and you have IP-controlled USB-power.
(Guess I have to order one to play with ;-) )

On the other hand iirc the Broadcom-SOC found in the RPi
has a hardware-watchdog the linux-kernel has a driver
for. So you might consider going for SBD (no shared disk)
with watchdog-fencing as well.
But that would require you to add a 3rd node (or some
kind of shared disk).
Andrew's blog article is a nice introduction:
http://blog.clusterlabs.org/blog/2015/sbd-fun-and-profit

Klaus