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Zookeeper, mail # user - Rolling upgrades


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Jordan Zimmerman 2012-03-08, 23:30
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RE: Rolling upgrades
Alexander Shraer 2012-03-08, 23:39
I don't think there is a problem if you do it as you say, or even if you just change the config files of all servers at once and restart them, because a majority of the new config
necessarily intersects with a majority of the old one, so a server who has the latest state will be elected leader.

Alex

> -----Original Message-----
> From: Jordan Zimmerman [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, March 08, 2012 3:31 PM
> To: [EMAIL PROTECTED]
> Subject: Rolling upgrades
>
> I've been reading the archives regarding rolling upgrades. Here's the
> scenario, given a stable ensemble:
>
> ZK1 <-> ZK2 <-> ZK3
>
> In the above, the zoo.cfg for each server looks like this (pseudo):
> server.1=ZK1
> server.2=ZK2
> server.3=ZK3
>
> I want to add a new server, ZK4. If I understand this correctly, I'd
> bring up ZK4 with this config:
> server.1=ZK1
> server.2=ZK2
> server.3=ZK3
> server.4=ZK4
>
> At this point, though, the configs don't match in the ensemble. How do
> the ZK instances handle this?
>
> Continuing...
>
> Once ZK4 is up, ZK1 would get the new config and get restarted. Once
> ZK1 is up, ZK2 gets new config, etc.
>
> At each point of config change, the cluster is in a confused state
> about the config. Is there code in ZK to handle this?
>
> -JZ
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Jordan Zimmerman 2012-03-09, 00:10
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Ted Dunning 2012-03-09, 00:24
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Ted Dunning 2012-03-09, 00:25
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Alexander Shraer 2012-03-09, 00:15