Hey,
So as far as I know this feature you require is not yet/or will be available. You can specify the error checking policy but if a controller is lost I dont think this will function as you would like it to. Hopefully, one of the developers will be able to give you a better answer. It would be cool if writes could be suspended but reads still enabled if a known controller was lost, but because controllers can go down for several reasons, like purposeful maintenance where writes could still be allowed because they can be easily recovered if a checkpoint exists, it may not be feasible. Im sure there are long drawn out ways to force the functionality you want, but hopefully you can find a solution that is readily available. (i.e. Monitoring using JMX and executing commands based on conditions defined by your application). I am dealing with a similar failure case situation currently and our idea for a solution is to simply monitor the link between controllers using an external service and upon failure shutdown systems during off ours and manually merge and recover. Now of course we are not using controllers in-between wide area networks so this fail point is minimized where in your case could occur quite often!!! I would also love to hear about a more efficient method to handle this fail point! Martin Dale Lyness MagnetStreet [EMAIL PROTECTED] Office: (763) 450-7503 Cell: (715) 630-0296 _____ From: Rafael Rossignol Felipe [mailto:[EMAIL PROTECTED] Sent: Thursday, July 24, 2008 9:09 AM To: [EMAIL PROTECTED]; Sequoia general mailing list Subject: Re: [Sequoia] Structural ideas Thanks Martin Do you know if is possible to configure the RequestManager to not execute write statements on backends if one of them fails? if possible my problem will solved 2008/7/24 Martin Lyness <[EMAIL PROTECTED]>: I think you are describing the Split-Brain scenario where the two controllers are still operational but they don't see each other, is this correct? I'm not the sequoia expert but I figure I would shoot you a quick email to help while you wait on the experts :-). As far as I know this is the proper functionality (i.e. not using an updating queue), and you should monitor this link so that you can observe when failure occurs between the controllers and perform recovery steps accordingly. It would be interesting to automatically handle this type of failure, but how would you know that it is a simple network communication failure versus something more serious and if there is possible data corruption on the other database. But like I said I'm not the expert so I'm looking forward to hearing their responses. Martin Dale Lyness MagnetStreet [EMAIL PROTECTED] Office: (763) 450-7503 Cell: (715) 630-0296 _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rafael Rossignol Felipe Sent: Thursday, July 24, 2008 6:45 AM To: [email protected] Subject: [Sequoia] Structural ideas Hi everybody, I´m newbie on Sequoia, but i've read lots of documentation, and made some tests. I have an Application in two subsidiaries of the same company. In both subsidiaries i have a jBoss with One application that access a local database. something like this: http://br.geocities.com/rafaelrfelipe/today.png The problem is: the data must be distributed! If an insert is executed at subsidiary 1, a select executed in subsidiary 2 must retrieve all data (includes this specific insert) Well, i´ve chose use Sequoia to help me make it work. I made a test configuring one controller with two backends (each one pointing to a one subsidiary), so i executed a update command. The update was successful and the data was updated on two oracles databases. But there´s a problem, the preferential link is unstable, so i unplug the net cable from one database server to see the failover algorithm in action (I though there was a queue of statements that wait the link become available to start to update after server is back). So i discovered that if a backend is down, sequoia does not updates the data after it´s back. I don´t know if I've configured something wrong or if this feature do not exist at all (a queue of update statements to be executed after backend returns of a crash). Is this feature possible? I used Raidb 1 algorithm I think that my final scenery it´s some like this: http://br.geocities.com/rafaelrfelipe/idea.png Is this scenery possible? Thanks for any response Rafael _______________________________________________ Sequoia mailing list [email protected] https://forge.continuent.org/mailman/listinfo/sequoia
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