On Thu, 22 Jul 2021 12:56:40 +0300 Andrei Borzenkov <arvidj...@gmail.com> wrote:
> On Thu, Jul 22, 2021 at 12:43 PM Jehan-Guillaume de Rorthais > <j...@dalibo.com> wrote: > > > > On Wed, 21 Jul 2021 12:45:40 -0400 > > Digimer <li...@alteeve.ca> wrote: > > > > > On 2021-07-21 3:26 a.m., Jehan-Guillaume de Rorthais wrote: > > > > Hi, > > > > > > > > On Wed, 21 Jul 2021 04:28:30 +0000 (UTC) > > > > Strahil Nikolov via Users <users@clusterlabs.org> wrote: > > > > > > > >> Hi, > > > >> consider using a 3rd system as a Q disk. Also, you can use iscsi from > > > >> that node as a SBD device, so you will have proper fencing .If you > > > >> don't have a hardware watchdog device, you can use softdog kernel > > > >> module for that. Best > > > > > > > > Having 3 nodes for quorum AND watchdog (using softdog in last resort) is > > > > enough, isn't it? > > > > But yes, having a shared storage to add a SBD device is even better. > > > > > > > > Regards, > > > > > > The third node with storage-based death is a way of creating a fence > > > configuration. > > > > Yes, poison pill. > > > > > It works because it's fencing, not because it's quorum. > > > > That's not what I said. Two node + sbd is safe. OK. > > > > My consideration/question was: 3 nodes + watchdog, without storage-based > > death, looks good enough to me. Do I miss something? > > > > From an integrity point of view it is equivalent to SBD. SBD at the > end relies on a watchdog as well. So if you have a reliable hardware > watchdog it should be OK. > > From an operational point of view pacemaker does not have the notion > of "cluster wide shutdown". Which means - as soon as you stop > pacemaker on two nodes the third node will commit suicide because it > goes out of quorum. Last man standing may help here, I have not tried > it in true three node cluster. This does not happen with SBD as long > as storage remains accessible. Ok, understood. Thanks for the details Andrei! _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/