hadoop-zookeeper-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Flavio Junqueira " <...@yahoo-inc.com>
Subject RE: Dynamic server management?
Date Mon, 17 Nov 2008 14:18:58 GMT
Hi Thomas, In the scenario you describe, 1 and 2 won't make any progress as
they are not part of a component that contains a quorum (a majority in this
current implementation). Servers 3,4,5 will elect a leader (if they don't
have one yet), and will make progress independently. Once the segmentation
heals, 1 and 2 will synchronize with the current leader. 

Thanks,
-Flavio 

> -----Original Message-----
> From: Kiesslich, Thomas [mailto:thomas.kiesslich@siemens.com]
> Sent: Monday, November 17, 2008 2:04 PM
> To: zookeeper-user@hadoop.apache.org
> Subject: AW: Dynamic server management?
> 
> Hi Flavio,
> 
> Thank you for the information.
> 
> So how do you handle than the following scenario?
> You have 5 servers and temporary network segmentation, where server 1 and
> 2 cannot talk to 3,4 and 5. Will server 1 and 2 do a new leader election
> for their partition, as well server 3,4 and 5 for their partition? If yes,
> how do they synchronize if they can reach each other again?
> 
> 
> Mit freundlichen Grüßen / With best regards
> Thomas Kießlich
> 
> Siemens Enterprise Communications GmbH & Co. KG
> HiPath Applications
> 
> SEN LIP DA 11
> Schertlinstr. 8
> 81379 Munich, Germany
> 
> -----Ursprüngliche Nachricht-----
> Von: Flavio Junqueira [mailto:fpj@yahoo-inc.com]
> Gesendet: Montag, 17. November 2008 13:49
> An: zookeeper-user@hadoop.apache.org
> Betreff: RE: Dynamic server management?
> 
> Hi Thomas, We currently don't have such a feature of adding and removing
> servers dynamically, although we would like to, so we'll have it
> eventually.
> 
> Without a dynamic mechanism for adding and removing servers, your example
> is
> problematic. Suppose that you configure your ensemble to have 3 servers,
> and
> then you start only one. Your single server would say: "Hey, I'm alone so
> I
> should make progress independently". This is reasonable, right? Well, not
> really, because you can have the following alternative execution. You
> start
> your three servers, but there is a temporary network partition and server
> 1
> cannot talk to servers 2 and 3. Consequently, server 1 will make progress
> independently of 2 and 3, and their state will diverge.
> 
> Hope it helps.
> 
> -Flavio
> 
> > -----Original Message-----
> > From: Kiesslich, Thomas [mailto:thomas.kiesslich@siemens.com]
> > Sent: Monday, November 17, 2008 11:46 AM
> > To: zookeeper-user@hadoop.apache.org
> > Subject: Dynamic server management?
> >
> > Hi all,
> >
> > I am evaluating ZooKeeper as a discovery protocol. I want to change the
> > number of servers that build up  ensemble during runtime of an existing
> > number servers. Is that possible or do I have to change the
> configuration
> > and restart all servers? I found that if you have 3 servers configured
> and
> > startup the first it is continously looking for the at least one other
> > server. Is it really necessary to do that? If the first server does not
> > find anyone else, it could elect itself as the leader. If the next
> server
> > starts up the can redo the election I guess.
> > Could you please help me with these questions? Thank you.
> >
> >
> >
> > Mit freundlichen Grüßen / With best regards
> > Thomas Kießlich
> >
> > Siemens Enterprise Communications GmbH & Co. KG
> > HiPath Applications
> >
> > SEN LIP DA 11
> > Schertlinstr. 8
> > 81379 Munich, Germany
> >
> > Phone: +49 (89) 722-32483
> > Fax: +49 (89) 722-40560
> > Email: thomas.kiesslich@siemens.com
> >
> > Communication for the open minded
> > www.siemens.de/open
> > www.siemens.com/open
> >
> > Siemens Enterprise Communications GmbH & Co. KG
> > Managing Directors: Andreas Bernhardt, Reinhard Benditte,
> > Gerhard Otterbach, Thomas Zimmermann
> > Registered offices: Munich
> > Commercial registry Munich, HRA 88546
> > WEEE-Reg.-No. DE 27980375
> > General Partner:
> > Siemens Enterprise Communications Management GmbH
> > Registered offices: Munich
> > Commercial registry: Munich, HRB 163415
> >
> > Wichtiger Hinweis: Diese Information ist für den Gebrauch durch die
> Person
> > oder die Firma/Organisation bestimmt, die in der Empfängeradresse
> benannt
> > ist. Wenn Sie nicht der angegebene Empfänger sind, nehmen Sie bitte zur
> > Kenntnis, daß Weitergabe, Kopieren, Verteilung oder Nutzung des Inhalts
> > dieser Email-Übertragung unzulässig ist. Falls Sie diese Email
> irrtümlich
> > erhalten haben, benachrichtigen Sie den Absender bitte unverzüglich
> > telefonisch oder durch eine Email. Vielen Dank.
> >
> > Important Note: This e-mail may contain trade secrets or privileged,
> > undisclosed or otherwise confidential information. If you have received
> > this e-mail in error, you are hereby notified that any review, copying
> or
> > distribution of it is strictly prohibited. Please inform us immediately
> > and destroy the original transmittal. Thank you for your cooperation.
> >
> 



Mime
View raw message