On Tue, 18 Aug 2020 08:21:50 +0200 Klaus Wenninger <kwenn...@redhat.com> wrote:
> On 8/18/20 7:49 AM, Andrei Borzenkov wrote: > > 17.08.2020 23:39, Jehan-Guillaume de Rorthais пишет: > >> On Mon, 17 Aug 2020 10:19:45 -0500 > >> Ken Gaillot <kgail...@redhat.com> wrote: > >> > >>> On Fri, 2020-08-14 at 15:09 +0200, Gabriele Bulfon wrote: > >>>> Thanks to all your suggestions, I now have the systems with stonith > >>>> configured on ipmi. > >>> A word of caution: if the IPMI is on-board -- i.e. it shares the same > >>> power supply as the computer -- power becomes a single point of > >>> failure. If the node loses power, the other node can't fence because > >>> the IPMI is also down, and the cluster can't recover. > >>> > >>> Some on-board IPMI controllers can share an Ethernet port with the main > >>> computer, which would be a similar situation. > >>> > >>> It's best to have a backup fencing method when using IPMI as the > >>> primary fencing method. An example would be an intelligent power switch > >>> or sbd. > >> How SBD would be useful in this scenario? Poison pill will not be > >> swallowed by the dead node... Is it just to wait for the watchdog timeout? > >> > > Node is expected to commit suicide if SBD lost access to shared block > > device. So either node swallowed poison pill and died or node died > > because it realized it was impossible to see poison pill or node was > > dead already. After watchdog timeout (twice watchdog timeout for safety) > > we assume node is dead. > Yes, like this a suicide via watchdog will be triggered if there are > issues with thedisk. This is why it is important to have a reliable > watchdog with SBD even whenusing poison pill. As this alone would > make a single shared disk a SPOF, runningwith pacemaker integration > (default) a node with SBD will survive despite ofloosing the disk > when it has quorum and pacemaker looks healthy. As corosync-quorum > in 2-node-mode obviously won't be fit for this purpose SBD will switch > to checking for presence of both nodes if 2-node-flag is set. > > Sorry for the lengthy explanation but the full picture is required > to understand whyit is sufficiently reliable and useful if configured Thank you Andrei and Klaus for the explanation. Regards, _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/
