[Pacemaker] Fixed! - Re: Problem with dual-PDU fencing node with redundant PSUs

[Vladislav Bogdanov]

29.06.2013 02:22, Andrew Beekhof wrote:
> 
> On 29/06/2013, at 12:22 AM, Digimer <lists at alteeve.ca> wrote:
> 
>> On 06/28/2013 06:21 AM, Andrew Beekhof wrote:
>>>
>>> On 28/06/2013, at 5:22 PM, Lars Marowsky-Bree <lmb at suse.com> wrote:
>>>
>>>> On 2013-06-27T12:53:01, Digimer <lists at alteeve.ca> wrote:
>>>>
>>>>> primitive fence_n01_psu1_off stonith:fence_apc_snmp \
>>>>>       params ipaddr="an-p01" pcmk_reboot_action="off" port="1"
>>>>> pcmk_host_list="an-c03n01.alteeve.ca"
>>>>> primitive fence_n01_psu1_on stonith:fence_apc_snmp \
>>>>>       params ipaddr="an-p01" pcmk_reboot_action="on" port="1"
>>>>> pcmk_host_list="an-c03n01.alteeve.ca"
>>>>
>>>> So every device twice, including location constraints? I see potential
>>>> for optimization by improving how the fence code handles this ... That's
>>>> abhorrently complex. (And I'm not sure the 'action' parameter ought to
>>>> be overwritten.)
>>>
>>> I'm not crazy about it either because it means the device is tied to a specific command.
>>> But it seems to be something all the RHCS people try to do...
>>
>> Maybe something in the rhcs water cooler made us all mad... ;)
>>
>>>> Glad you got it working, though.
>>>>
>>>>> location loc_fence_n01_ipmi fence_n01_ipmi -inf: an-c03n01.alteeve.ca
>>>> [...]
>>>>
>>>> I'm not sure you need any of these location constraints, by the way. Did
>>>> you test if it works without them?
>>>>
>>>>> Again, this is after just one test. I will want to test it several more
>>>>> times before I consider it reliable. Ideally, I would love to hear
>>>>> Andrew or others confirm this looks sane/correct.
>>>>
>>>> It looks correct, but not quite sane. ;-) That seems not to be
>>>> something you can address, though. I'm thinking that fencing topology
>>>> should be smart enough to, if multiple fencing devices are specified, to
>>>> know how to expand them to "first all off (if off fails anywhere, it's a
>>>> failure), then all on (if on fails, it is not a failure)". That'd
>>>> greatly simplify the syntax.
>>>
>>> The RH agents have apparently already been updated to support multiple ports.
>>> I'm really not keen on having the stonith-ng doing this.
>>
>> This doesn't help people who have dual power rails/PDUs for power
>> redundancy.
> 
> I'm yet to be convinced that having two PDUs is helping those people in the first place.
> If it were actually useful, I suspect more than two/three people would have asked for it in the last decade.

I'm just silently waiting for this to happen.
Although I use different fencing scheme (and plan to use even more
different one), that is very nice fall-back path for me. And I strongly
prefer all complexities like reboot -> off-off-on-on to be hidden from
the configuration. Naturally, that is task for the entity which has
whole picture of what to do - stonithd. Just my 'IMHO'.

And, to PSU/PDU. I, like Digimer, always separate power circuits as much
as possible. Of course I always use redundant PSUs.

Vladislav