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Posted to user@zookeeper.apache.org by David Nickerson <da...@gmail.com> on 2012/06/18 19:28:01 UTC

Adding to a quorum

Say I have a quorum of four ZooKeeper servers. Is there any way I can add a
fifth ZooKeeper to the quorum without interrupting the service? I see some
work on making it easy
here<https://issues.apache.org/jira/browse/ZOOKEEPER-107>and
here<https://cwiki.apache.org/confluence/display/ZOOKEEPER/ClusterMembership>,
but I'm wondering if there's currently any way to do it at all. Would it
work to start up the fifth pointing to all of the others, then one-by-one
restart the others, updating their configuration to include the fifth?

Re: Adding to a quorum

Posted by Ted dunning <te...@gmail.com>.



On Jun 18, 2012, at 3:22 PM, David Nickerson <da...@gmail.com> wrote:

> Ted: Thanks for the answer. The quorum of four servers was hypothetical;
> our business has not incorporated ZooKeeper yet.

Ahh..


> Also, I would imagine that this solution wouldn't work for two servers,
> because we'd lose the quorum?

It would work fine. Start the new server first.   Then update  the two existing servers.

This shouldn't occur, however, because you don't normally have an even number 

> 
> Jordan: Thanks for the link, that looks like it'll be very helpful.
> 
> On Mon, Jun 18, 2012 at 2:35 PM, Jordan Zimmerman <jz...@netflix.com>wrote:
> 
>> FYI - have a look at our Exhibitor system which makes upgrades/additions
>> easier to manage.
>> 
>> https://github.com/Netflix/exhibitor
>> 
>> 
>> On 6/18/12 11:26 AM, "Ted Dunning" <te...@gmail.com> wrote:
>> 
>>> Yes.  Updating and restarting works fine.
>>> 
>>> One does wonder why you have *four* servers now.  That generally doesn't
>>> provide any advantage over having three servers.
>>> 
>>> On Mon, Jun 18, 2012 at 10:28 AM, David Nickerson <
>>> davidnickerson4mailinglists@gmail.com> wrote:
>>> 
>>>> Say I have a quorum of four ZooKeeper servers. Is there any way I can
>>>> add a
>>>> fifth ZooKeeper to the quorum without interrupting the service? I see
>>>> some
>>>> work on making it easy
>>>> here<https://issues.apache.org/jira/browse/ZOOKEEPER-107>and
>>>> here<
>>>> 
>>>> https://cwiki.apache.org/confluence/display/ZOOKEEPER/ClusterMembership
>>> ,
>>>> but I'm wondering if there's currently any way to do it at all. Would it
>>>> work to start up the fifth pointing to all of the others, then
>>>> one-by-one
>>>> restart the others, updating their configuration to include the fifth?
>>>> 
>> 
>> 

Re: Adding to a quorum

Posted by David Nickerson <da...@gmail.com>.
Ted: Thanks for the answer. The quorum of four servers was hypothetical;
our business has not incorporated ZooKeeper yet.

Also, I would imagine that this solution wouldn't work for two servers,
because we'd lose the quorum?

Jordan: Thanks for the link, that looks like it'll be very helpful.

On Mon, Jun 18, 2012 at 2:35 PM, Jordan Zimmerman <jz...@netflix.com>wrote:

> FYI - have a look at our Exhibitor system which makes upgrades/additions
> easier to manage.
>
> https://github.com/Netflix/exhibitor
>
>
> On 6/18/12 11:26 AM, "Ted Dunning" <te...@gmail.com> wrote:
>
> >Yes.  Updating and restarting works fine.
> >
> >One does wonder why you have *four* servers now.  That generally doesn't
> >provide any advantage over having three servers.
> >
> >On Mon, Jun 18, 2012 at 10:28 AM, David Nickerson <
> >davidnickerson4mailinglists@gmail.com> wrote:
> >
> >> Say I have a quorum of four ZooKeeper servers. Is there any way I can
> >>add a
> >> fifth ZooKeeper to the quorum without interrupting the service? I see
> >>some
> >> work on making it easy
> >> here<https://issues.apache.org/jira/browse/ZOOKEEPER-107>and
> >> here<
> >>
> >>https://cwiki.apache.org/confluence/display/ZOOKEEPER/ClusterMembership
> >,
> >> but I'm wondering if there's currently any way to do it at all. Would it
> >> work to start up the fifth pointing to all of the others, then
> >>one-by-one
> >> restart the others, updating their configuration to include the fifth?
> >>
>
>

Re: Adding to a quorum

Posted by Jordan Zimmerman <jz...@netflix.com>.
FYI - have a look at our Exhibitor system which makes upgrades/additions
easier to manage.

https://github.com/Netflix/exhibitor


On 6/18/12 11:26 AM, "Ted Dunning" <te...@gmail.com> wrote:

>Yes.  Updating and restarting works fine.
>
>One does wonder why you have *four* servers now.  That generally doesn't
>provide any advantage over having three servers.
>
>On Mon, Jun 18, 2012 at 10:28 AM, David Nickerson <
>davidnickerson4mailinglists@gmail.com> wrote:
>
>> Say I have a quorum of four ZooKeeper servers. Is there any way I can
>>add a
>> fifth ZooKeeper to the quorum without interrupting the service? I see
>>some
>> work on making it easy
>> here<https://issues.apache.org/jira/browse/ZOOKEEPER-107>and
>> here<
>> 
>>https://cwiki.apache.org/confluence/display/ZOOKEEPER/ClusterMembership>,
>> but I'm wondering if there's currently any way to do it at all. Would it
>> work to start up the fifth pointing to all of the others, then
>>one-by-one
>> restart the others, updating their configuration to include the fifth?
>>


Re: Adding to a quorum

Posted by Ted Dunning <te...@gmail.com>.
Yes.  Updating and restarting works fine.

One does wonder why you have *four* servers now.  That generally doesn't
provide any advantage over having three servers.

On Mon, Jun 18, 2012 at 10:28 AM, David Nickerson <
davidnickerson4mailinglists@gmail.com> wrote:

> Say I have a quorum of four ZooKeeper servers. Is there any way I can add a
> fifth ZooKeeper to the quorum without interrupting the service? I see some
> work on making it easy
> here<https://issues.apache.org/jira/browse/ZOOKEEPER-107>and
> here<
> https://cwiki.apache.org/confluence/display/ZOOKEEPER/ClusterMembership>,
> but I'm wondering if there's currently any way to do it at all. Would it
> work to start up the fifth pointing to all of the others, then one-by-one
> restart the others, updating their configuration to include the fifth?
>