On 09/08/2015 05:33 PM, Andrew Beekhof wrote: > >> On 9 Sep 2015, at 12:13 am, Ken Gaillot <[email protected]> wrote: >> >> On 09/07/2015 07:48 AM, Jorge Fábregas wrote: >>> On 09/07/2015 03:27 AM, Digimer wrote: >>>> And this is why I am nervous; It is always ideal to have a primary fence >>>> method that has a method of confirming the 'off' state. IPMI fencing can >>>> do this, as can hypervisor-based fence methods like fence_virsh and >>>> fence_xvm. >>> >>> Hi Digimer, >>> >>> Yes, I thought that confirmation was kind of sacred but now I know it's >>> not always possible. >>> >>>> I would use IPMI (iLO, DRAC, etc) as the primary fence method and >>>> something else as a secondary, backup method. You can use SBD + watchdog >>>> as the backup method, or as I do, a pair of switched PDUs (I find APC >>>> brand to be very fast in fencing). >>> >>> This sounds great. Is there a way to specify a primary & secondary >>> fencing device? I haven't seen a way to specify such hierarchy in >>> pacemaker. >> >> Good news/bad news: >> >> Yes, pacemaker supports complex hierarchies of multiple fencing devices, >> which it calls "fencing topology". There is a small example at >> http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#_advanced_stonith_configurations >> >> Unfortunately, sbd is not supported in fencing topologies. > > Another way to look at it, is that sbd is only supported in fencing > topologies - just not explicit ones. > Self-termination is always the least best option, so we’ll only use it if all > other options (including topologies) are exhausted. > But we’ll do so automatically.
Ah, that's a better situation than I realized. In that case, it would be easy to add a primary fencing device (or multiple devices in a topology), and enable sbd, to create the same effect as having sbd as the last level in a topology. Sbd just wouldn't be explicitly listed in a topology configuration. >> Pacemaker >> hooks into sbd via dedicated internal logic, not a conventional fence >> agent, so it's treated differently. You might want to open an RFE bug >> either upstream or with your OS vendor if you want to put it on the >> radar, but sbd isn't entirely under Pacemaker's control, so I'm not sure >> how feasible it would be. _______________________________________________ Users mailing list: [email protected] http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
