Thank you for your reply. If you have a time, could you tell me what happens in Sequoia when a controller suffers intermittent communication failure in network devices such as a switch or NIC? For example, for a couple of minutes, an NIC is not responded. I am not sure if this is possible failure scenario in real, though. Thank you for the paper list.
On Mon, Dec 8, 2008 at 12:52 PM, Emmanuel Cecchet <[EMAIL PROTECTED]>wrote: > Hi, > > There is no solution to the partitioning problem if you need consistency. > The first impossibility proof appeared in Brian A. Coan, Brian M. Oki, and > Elliot K. Kolodner. "Limitations on Database Availability when Networks > Partition." Proceedings of the Fifth Annual ACM Symposium on Principles of > Distributed Computing (1986), pp. 187–194. > If your machines are connected to the same network switch, they will all > lose connectivity simultaneously if the switch goes down. You can then have > 2 networks with something like heartbeat (the HA tool) for failover from one > network to the other. > If someone artificially introduces a network partition by misconfiguring > the network (bad firewall or VPN setup) the you will have to do > reconciliation (which cannot be done automatically). Some people have been > thinking about the problem: Asplund, M. and Nadjm-Tehrani, S. 2006. > Post-partition reconciliation protocols for maintaining consistency. In > /Proceedings of the 2006 ACM Symposium on Applied Computing/ (Dijon, France, > April 23 - 27, 2006). SAC '06. ACM, New York, NY, 710-717. > > In all cases, you have to try to avoid partitions by designing carefully > your network configuration. You will only be able to detect a partition when > it is too late and what you want to do for reconciliation is application > specific. > > Hope this helps, > Emmanuel > > I am running two controllers with RAIDB-1 scheme. But, the problem is when >> network is partitioned because of a switch failure. >> In this scenario, two controllers will receive user's requests from each. >> So, it will make two backends inconsistent. >> >From the Bianca's papers I reallized that this network partition very >> often can happen. >> >> When I look at this mailing-list, Emmanuel suggested to unify database >> communication path and user request path in network topology. >> But, in our case, databases are already communicating via gigabit network, >> seperated from outside communication channel. >> >> And, I read the "C-JDBC Horizontal Scalability: A controller replication >> user guide", and understood I need to make a JMX client which >> listens from JMX notification of Sequoia controllers. I think that this >> process will need to stop one controller, when two controllers are >> partitioned, or switch a backend database to the read-only mode. >> >> At this point, I have a quick question. I wonder if there is another >> better solution dealing with this sort of network partition in Sequoia. >> Thank you for your reading. >> >> >> Best, >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> Sequoia mailing list >> [email protected] >> https://forge.continuent.org/mailman/listinfo/sequoia >> > > > -- > Emmanuel Cecchet > FTO @ Frog Thinker Open Source Development & Consulting > -- > Web: http://www.frogthinker.org > email: [EMAIL PROTECTED] > Skype: emmanuel_cecchet > > _______________________________________________ > Sequoia mailing list > [email protected] > https://forge.continuent.org/mailman/listinfo/sequoia > -- 여호와는 네게 복을 주시고 너를 지키시기를 원하며 여호와는 그 얼굴을 네게 비추사 은혜 베푸시기를 원하며 여호와는 그 얼굴을 네게로 향하여 드사 평강 주시기를 원하노라 (민수기 6:24-26)
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