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From Something Something <mailinglist...@gmail.com>
Subject Re: Zookeeper multiserver setup?
Date Tue, 08 May 2012 22:46:06 GMT
Thanks.  Took your advice & cut down the number to 5 instances.  Confirmed
that one of them is a leader & the rest are followers.  Now on to
installing HBase.  Thanks again.

On Tue, May 8, 2012 at 3:19 PM, Jordan Zimmerman <jzimmerman@netflix.com>wrote:

> For most uses, 3 instances is enough. For heavy usage, 5 instances can be
> used. ZooKeeper write performance degrades with the number of instances
> added. There's a lot of doc on the net about this.
>
> A ZNode is a data entry in the ZooKeeper database. An instance is a server
> running the ZooKeeper software.
>
> -JZ
>
> On 5/8/12 3:13 PM, "Something Something" <mailinglists19@gmail.com> wrote:
>
> >We have a cluster of 17 machines.  Somewhere in the HBase documentation I
> >read - usually we should divide by 2 & use an odd number.  May be I
> >mis-read.  That's why I started Zookeeper on 9 machines.  I guess, I don't
> >understand the difference between Nodes & Instance.  I expected ZKNodes to
> >be 9.  Please explain.  Thanks a lot for your help.
> >
> >On Tue, May 8, 2012 at 3:05 PM, Jordan Zimmerman
> ><jzimmerman@netflix.com>wrote:
> >
> >> You have 9 instances? That's a lot. Why so many?
> >>
> >> I believe the "Node" field in the stat is the number of ZKNodes, not
> >> instances in the ensemble. That stat looks good. It means that that
> >> instance is serving requests as a "follower" instance (one of the
> >> instances will be the leader).
> >>
> >> -JZ
> >>
> >> On 5/8/12 2:54 PM, "Something Something" <mailinglists19@gmail.com>
> >>wrote:
> >>
> >> >Hmm...
> >> >
> >> >
> >> >Trying 127.0.0.1...
> >> >Connected to localhost.
> >> >Escape character is '^]'.
> >> >stat
> >> >Zookeeper version: 3.3.4-cdh3u3--1, built on 01/26/2012 20:09 GMT
> >> >Clients:
> >> > /127.0.0.1:42510[0](queued=0,recved=1,sent=0)
> >> >
> >> >Latency min/avg/max: 0/0/0
> >> >Received: 4
> >> >Sent: 3
> >> >Outstanding: 0
> >> >Zxid: 0x100000000
> >> >Mode: follower
> >> >Node count: 11
> >> >Connection closed by foreign host.
> >> >
> >> >
> >> >Not sure I understand this output.  I have 9 nodes in the ensemble.
> >> >
> >> >On Tue, May 8, 2012 at 2:45 PM, Jordan Zimmerman
> >> ><jzimmerman@netflix.com>wrote:
> >> >
> >> >> Yes - they should. Keep in mind that the zoo.cfg, and the ID file
> >>must
> >> >>be
> >> >> correct and in agreement on each instance. You can do a stat on each
> >> >> instance to see what state it's in:
> >> >>
> >> >>    >telnet localhost 2181
> >> >>     stat
> >> >>
> >> >> -JZ
> >> >>
> >> >> On 5/8/12 2:43 PM, "Something Something" <mailinglists19@gmail.com>
> >> >>wrote:
> >> >>
> >> >> >Thanks Jordan.  Will definitely look at the cluster management
tool.
> >> >>In
> >> >> >the mean time, am I correct with my assumption in #4?  Once all
of
> >>them
> >> >> >are
> >> >> >started they would automagically start talking to each other, right?
> >> >> >
> >> >> >
> >> >> >On Tue, May 8, 2012 at 2:36 PM, Jordan Zimmerman
> >> >> ><jzimmerman@netflix.com>wrote:
> >> >> >
> >> >> >> Yes, you must start them all individually. ZooKeeper does
not
> >> >>currently
> >> >> >> have any cluster-wide management tools built in.
> >> >> >>
> >> >> >> FYI - we've open sourced a cluster management tool for ZooKeeper.
> >> >>Please
> >> >> >> have a look:
> >> >> >>
> >> >> >>        https://github.com/Netflix/exhibitor
> >> >> >>
> >> >> >> On 5/8/12 2:31 PM, "Something Something"
> >><mailinglists19@gmail.com>
> >> >> >>wrote:
> >> >> >>
> >> >> >> >Hello,
> >> >> >> >
> >> >> >> >Trying to follow directions from here:
> >> >> >> >
> >> >> >>
> >> >> >>
> >> >>
> >> >>
> >>
> >>
> http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServe
> >> >> >>r
> >> >> >> >Setup
> >> >> >> >
> >> >> >> >to setup a cluster of zookeepers.
> >> >> >> >
> >> >> >> >Questions:
> >> >> >> >
> >> >> >> >1)  If everything is setup correctly, do I have to go
to each
> >> >>machine
> >> >> >>and
> >> >> >> >start Zookeeper server in each of them individually?
> >> >> >> >2)  I was thinking if I start it on one master machine
(well
> >> >>there's no
> >> >> >> >real master) then all zookeepers in the quorum would be
started,
> >>but
> >> >> >>this
> >> >> >> >is not how it works correct?
> >> >> >> >3)  If I start individually, then I get messages saying
the other
> >> >> >> >zookeepers haven't started.  Is that just a warning?
> >> >> >> >4)  When all of them are started, would they all be able
to talk
> >>to
> >> >> >>each
> >> >> >> >other?
> >> >> >> >
> >> >> >> >Sorry for the dumb questions and thanks for the help.
> >> >> >>
> >> >> >>
> >> >>
> >> >>
> >>
> >>
>
>

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