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Date: Fri, 5 Mar 2010 16:26:26 -0800
Message-ID: <86e557c1003051626m705541c9gdecbf1b925ea2bf5@mail.gmail.com>
Subject: Re: Usage of myId
From: Nick Dimiduk <ndimiduk@gmail.com>
To: zookeeper-user@hadoop.apache.org
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I think automating this assignment has been discussed in the past. IIRC,
some combination of MAC address and pid or timestamp would be sufficient to
uniquely identify a ZK instance. There may be some detail I'm forgetting
about maintaining the ID between process restarts, making these ephemeral
values unacceptable.

Cheers,
-Nick

On Mon, Mar 1, 2010 at 6:56 PM, Henry Robinson <henry@cloudera.com> wrote:

> If you have two servers with the same myid, two servers will identify
> themselves as the 'same' machine X in a ZooKeeper ensemble. This id is used
> to map onto a hostname / port pair where messages for a given server are
> sent. Assuming a consistent quorum specification across all machines,
> messages for server X will only go to one machine and the other will think
> itself partitioned from the network.
>
> Servers need ids to distinguish themselves from other servers in order to
> break symmetry and successfully elect a leader.
>
> Henry
>
> On 27 February 2010 23:06, Qian Ye <yeqian.zju@gmail.com> wrote:
>
> > myid is used to identify your service instance, with its help, it is
> > possible to start more than one Zookeeper service on one computer. If the
> > configuration of myid is wrong, the service can not be started properly.
> >
> > On Sun, Feb 28, 2010 at 11:39 AM, Avinash Lakshman <
> > avinash.lakshman@gmail.com> wrote:
> >
> > > Why is this important? What breaks down if I have 2 servers with the
> same
> > > myId?
> > >
> > > Cheers
> > > A
> > >
> >
> >
> >
> > --
> > With Regards!
> >
> > Ye, Qian
> >
>
>
>
> --
> Henry Robinson
> Software Engineer
> Cloudera
> 415-994-6679
>

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