Thanks Ken, We will do our tests.
*Jonathan Vargas RodrÃguez* Founder and Solution Engineer Alkaid <https://alkaid.cr/> | Open Source Software * mail * jonathan.var...@alkaid.cr telf +506 4001 6259 Ext. 01 mobi +506 4001 6259 Ext. 51 <http://linkedin.com/in/jonathanvargas/> <https://plus.google.com/+JonathanVargas/> <https://www.facebook.com/alkaid.cr> <https://twitter.com/alkaidcr> 2015-06-25 8:57 GMT-06:00 Ken Gaillot <kgail...@redhat.com>: > On 06/24/2015 06:39 PM, Jonathan Vargas wrote: > > Thanks Ken. > > > > It's weird. Because we did tests and that did not happen. > > > > There is a node (named Z) without stonith/sbd resources assigned at all > and > > but it was the node that sent the fencing request to a crashed node (X). > > > > But this error appeared in its logs: "No route to host". > > > > It's obvious for us that if SBD isn't running on Z, and there is no > network > > access to that crashed node (X), then based on your answer, node Y which > > really had access to X via SBD had to initiate the fencing request. But > > this did not happen. > > > > In addition to this answer, I wonder if I could tell the cluster to avoid > > sending fencing requests from specific nodes, or at the other side: Tell > > the cluster which nodes are authorized to send fencing requests. > > > > Any idea? > > Yes, that's exactly what you have to do. > > By default, a cluster will be "opt-out" -- any resource can run on any > node unless you tell it otherwise. (You can change that to "opt-in", but > for simplicity I'll assume you're using the default.) > > The node that "runs" the fencing resource will monitor it, so if only > certain nodes can monitor the device, you need location constraints. How > you configure that depends on what tools you are using (pcs, crm or > low-level), but it's simple, you just say "this resource has this score > on this node". A score of -INFINITY means "never run this resource on > this node". > > For fencing resources, the cluster also need to know which hosts the > device can fence. By default the cluster will ask the fence agent by > running its "list" command. If that's not sufficient, you can configure > a static list of hosts that the device can fence. For details see: > > > http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#_special_treatment_of_stonith_resources > > > > On Jun 24, 2015 1:56 PM, "Ken Gaillot" <kgail...@redhat.com> wrote: > > > >> On 06/24/2015 12:20 PM, Jonathan Vargas wrote: > >>> Hi there, > >>> > >>> We have a 3-node cluster for OCFS2. > >>> > >>> When one of the nodes fail, it should be fenced. I noticed sometimes > one > >> of > >>> them is the one who sends the fencing message to the failing node, and > >>> sometimes it's the another. > >>> > >>> How the cluster decides which of the remaining active nodes will be the > >> one > >>> to tell the failed node to fence itself? > >>> > >>> Thanks. > >> > >> Fencing resources are assigned to a node like any other resource, even > >> though they don't really "run" anywhere. Assuming you've configured a > >> recurring monitor operation on the resource, that node will monitor the > >> device to ensure it's available. > >> > >> Because that node has "verified" (monitored) access to the device, the > >> cluster will prefer that node to execute the fencing if possible. So > >> it's just whatever node happened to be assigned the fencing resource. > >> > >> If for any reason the node with verified access can't do it, the cluster > >> will fall back to any other capable node. > >> > >>> *Jonathan Vargas RodrÃguez* > >>> Founder and Solution Engineer > >>> Alkaid <https://alkaid.cr/> | Open Source Software > >>> > >>> * mail * jonathan.var...@alkaid.cr > >>> telf +506 4001 6259 Ext. 01 > >>> mobi +506 4001 6259 Ext. 51 > >>> > >>> <http://linkedin.com/in/jonathanvargas/> > >>> <https://plus.google.com/+JonathanVargas/> > >>> <https://www.facebook.com/alkaid.cr> < > https://twitter.com/alkaidcr > >
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