On Wed, 13 Feb 2019 13:02:30 +0100 Maciej S <[email protected]> wrote:
> Thank you all for the answers. I can see your point, but anyway it seems > that fencing is like for additional precaution. It's not. > If my requirements allow some manual intervention in some cases (eg. > unknown resource state after failover), then I might go ahead without > fencing. At least until STONITH is not mandatory :) Well, then soon or later, we'll talk again about how to quickly restore your service and/or data. And the answer will be difficult to swallow. Good luck :) > pon., 11 lut 2019 o 17:54 Digimer <[email protected]> napisał(a): > > > On 2019-02-11 6:34 a.m., Maciej S wrote: > > > I was wondering if anyone can give a plain answer if fencing is really > > > needed in case there are no shared resources being used (as far as I > > > define shared resource). > > > > > > We want to use PAF or other Postgres (with replicated data files on the > > > local drives) failover agent together with Corosync, Pacemaker and > > > virtual IP resource and I am wondering if there is a need for fencing > > > (which is very close bind to an infrastructure) if a Pacemaker is > > > already controlling resources state. I know that in failover case there > > > might be a need to add functionality to recover master that entered > > > dirty shutdown state (eg. in case of power outage), but I can't see any > > > case where fencing is really necessary. Am I wrong? > > > > > > I was looking for a strict answer but I couldn't find one... > > > > > > Regards, > > > Maciej > > > > Fencing is as required as a wearing a seat belt in a car. You can > > physically make things work, but the first time you're "in an accident", > > you're screwed. > > > > Think of it this way; > > > > If services can run in two or more places at the same time without > > coordination, you don't need a cluster, just run things everywhere. If > > you need coordination though, you need fencing. > > > > The role of fencing is to force a node that has entered into an unknown > > state and force it into a known state. In a system that requires > > coordination, often times fencing is the only way to ensure sane operation. > > > > Also, with pacemaker v2, fencing (stonith) became mandatory at a > > programmatic level. > > > > -- > > Digimer > > Papers and Projects: https://alteeve.com/w/ > > "I am, somehow, less interested in the weight and convolutions of > > Einstein’s brain than in the near certainty that people of equal talent > > have lived and died in cotton fields and sweatshops." - Stephen Jay Gould > > -- Jehan-Guillaume de Rorthais Dalibo _______________________________________________ Users mailing list: [email protected] https://lists.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
