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

[Lars Marowsky-Bree]

On 2013-07-01T11:53:29, Digimer <lists at alteeve.ca> wrote:

> You are right, of course. Imagine though that the IPMI BMC's network
> port or cable could have silently failed some time before the node
> failed.

Pacemaker can monitor the fencing device if you configure a monitor
action for it, for exactly this reason.

> Yes, this is two simultaneous failues so not an overall SPoF, but
> likely enough that it should be addressed.

Yes ;-)

While it's conceivable that the *fencing* network switch doesn't have a
dual power supply and thus is affected by the outage (and very very few
management boards have two network ports so that you could connect them
to two), the answer here could be to - at least for two node scenarios -
just connect the management ports to a dedicated NIC on the other node.
(A ring topology for multiple nodes is conceivable.)

Then a single power failure could well cause both methods to fail.

Still, it's a double failure that we, officially, don't protect against
in all scenarios (the power failure + whatever causes the fence).




Regards,
    Lars

-- 
Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde