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From Patrick Hunt <ph...@apache.org>
Subject Re: Usage of myId
Date Sat, 06 Mar 2010 00:49:07 GMT
re previous discussion see this thread: 
http://www.mail-archive.com/zookeeper-user@hadoop.apache.org/msg00916.html

Patrick

Nick Dimiduk wrote:
> 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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