[Pacemaker] baring IPMI, what would you recommand for stonith?

[Digimer]

On 08/11/13 17:06, Jean-Francois Malouin wrote:
> * Digimer <lists at alteeve.ca> [20131107 21:46]:
>> On 07/11/13 20:38, Jean-Francois Malouin wrote:
>>> Hi,
>>> After a few smooth years with a very simple but sturdy 2-nodes HA
>>> cluster running pacemaker/drbd/Xen I've been given the task to build
>>> another one, but the hardware that they dropped on my lap doesn't have
>>> IPMI and I will definitely require stonith.
>>>
>>> What would you recommend? A switchable PDU/power fencing?
>>>
>>> Thanks!
>>> jf
>>
>> APC switched PDUs. I use a pair of AP7900 as backup fence devices in
>> case IPMI dies with the target node. It works extremely well. The
>> fence_apc_snmp handler is very well tested.
> 
> Thanks all for your comments. 
> Turns out that I can use IPMI by adding a daughter management card
> (smdc) to the mobos.
> 
> regards,
> jf

I still recommend the PDUs. If a node fails badly enough, and power is
lost, the IPMI BMC will lose power as well. In such a case, IPMI fencing
could not succeed, so the state of the failed node won't be confirmed.
Without external fencing, the surviving node(s) would remain blocked
(lest they risk a split-brain).

IPMI fencing is ideal, when it does work, because a "success" from an
IPMI device is near 100% certain. A PDU based fence depends on the
target's power cables being in the proper outlets. So if you use PDUs,
tie the cables into place to ensure no one moves them later.

Cheers!

-- 
Digimer
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