Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
enable_fencing=0 was only for testing purposes to see, how long it takes until the service on the active node will take over the work: it was about 5sec...drbd needs some time to update the state from Primary to Unknown....then fencing would start (but disabled) and the service on the active node continue to work (since now has access to the shared directory) In a production environment fencing will be enabled - but currently i don't have any fencing/stonith hardware - but i think the failover takes some seconds too ... Gesendet: Mittwoch, 13. Mai 2015 um 10:00 Uhr Von: Digimer <lists at alteeve.ca> An: "DRBD User" <DRBDUser at gmx.at>, drbd-user at lists.linbit.com Betreff: Re: [DRBD-user] Dual Primary Mode: Shared Directory blocked after node crash until reboot You can also not use your seat belt and tear down the highway. Doesn't mean it is a good idea. If you don't use proper fencing, you WILL run into trouble. When that happens, don't blame the software. You've been told directly and plainly that you *must* use fencing. If you don't, you will have a split-brain and it will be an avoidable disaster. Why not just use fencing? digimer On 13/05/15 03:43 AM, DRBD User wrote: > found a way without fencing: > > create /etc/dlm/dlm.conf and copy to all nodes > > * To use no fencing, use this line: > > enable_fencing=0 > > > > now if i pull the power plug it takes about 5sec and the other node continue to operate > > > Gesendet: Mittwoch, 13. Mai 2015 um 09:29 Uhr > Von: "DRBD User" <DRBDUser at gmx.at> > An: drbd-user at lists.linbit.com > Betreff: [DRBD-user] Dual Primary Mode: Shared Directory blocked after node crash until reboot > for manual ack i use these (RHEL7) : > > dlm_tool fence_ack nodeid > > > > Gesendet: Mittwoch, 13. Mai 2015 um 09:23 Uhr > Von: Digimer <lists at alteeve.ca> > An: "DRBD User" <DRBDUser at gmx.at>, drbd-user at lists.linbit.com > Betreff: Re: [DRBD-user] Dual Primary Mode: Shared Directory blocked after node crash until reboot > If you want automatic recovery of any sort, yes, it is required to avoid > a split brain. > > On 13/05/15 03:00 AM, DRBD User wrote: >> So for a primary/secondary setup I have to deal with fencing/stonith too ? >> >> I am using RHEL 7 and i can't find the fence_ack_manual command (for test purposes) ? >> >> >> >> Gesendet: Mittwoch, 13. Mai 2015 um 08:40 Uhr >> Von: Digimer <lists at alteeve.ca> >> An: "DRBD User" <DRBDUser at gmx.at>, drbd-user at lists.linbit.com >> Betreff: Re: [DRBD-user] Dual Primary Mode: Shared Directory blocked after node crash until reboot >> On 13/05/15 02:36 AM, DRBD User wrote: >>> Ok i understand: >>> >>> In a dual primary setup without a valid stonith configuration i have to wait until the crashed node is set to a *known* state: eg. using reboot, manual intervention. >>> >>> But what if the crashed node never gets alive: >>> Will the stonith setup set the state of the crashed node to a *known* state, so that the active node can continue to operate ? >>> Or do I have to intervene manually ? >>> >>> So for my plan to have a high available service (which saves its state to a shared directory) a primary/secondary setup may be the way to go - or i is fencing/stonith always a must ? >> >> The cluster (and DRBD) will remain blocked indefinitely. The only way to >> resume operation is when fencing succeeds or a human tells DRBD that the >> lost node is offline (via manual intervention). >> >> As an aside; Red Hat used to support manual fencing, but dropped support >> for it when RHEL 6 was released in 2010. The reason was that, on paper, >> manual fencing sounds fine. In practice, it was often misused and lead >> to split-brains. >> >> Consider; A cluster is locked up, people are screaming and the poor >> admin is trying to remember what to after a year of not touching things. >> s/he remembers about manually clearing the fence and then does so >> without first verifying the last node was off/dead. Is such a case, you >> have a split-brain and all the potential damage that goes with it. >> >> Get hardware fencing. It is the only sane and sensible option. >> >> -- >> Digimer >> Papers and Projects: https://alteeve.ca/w/ >> What if the cure for cancer is trapped in the mind of a person without >> access to education? >> _______________________________________________ >> drbd-user mailing list >> drbd-user at lists.linbit.com >> http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]]][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]]]] >> _______________________________________________ >> drbd-user mailing list >> drbd-user at lists.linbit.com >> http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]]] >> > > > -- > Digimer > Papers and Projects: https://alteeve.ca/w/[https://alteeve.ca/w/][https://alteeve.ca/w/[https://alteeve.ca/w/]][https://alteeve.ca/w/[https://alteeve.ca/w/][https://alteeve.ca/w/[https://alteeve.ca/w/]]] > What if the cure for cancer is trapped in the mind of a person without > access to education? > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user][http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]] > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user] > -- Digimer Papers and Projects: https://alteeve.ca/w/[https://alteeve.ca/w/] What if the cure for cancer is trapped in the mind of a person without access to education? _______________________________________________ drbd-user mailing list drbd-user at lists.linbit.com http://lists.linbit.com/mailman/listinfo/drbd-user[http://lists.linbit.com/mailman/listinfo/drbd-user]