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Subject: Re: Zookeeper Cross Datacenter Cluster
From: Jordan Zimmerman <jordan@jordanzimmerman.com>
In-Reply-To: <CAM3razgOhnwMB=EceiT=zrYf5-8DbEgYWYF29UL6kv49FfAmBg@mail.gmail.com>
Date: Mon, 6 Mar 2017 14:05:33 -0800
Cc: Le Cyberian <lecyberian@gmail.com>
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Message-Id: <0040A58A-7EC4-4FDD-BEC7-1A5C79BBAEFE@jordanzimmerman.com>
References: <CAM3razgOhnwMB=EceiT=zrYf5-8DbEgYWYF29UL6kv49FfAmBg@mail.gmail.com>
To: user@zookeeper.apache.org
archived-at: Mon, 06 Mar 2017 22:05:43 -0000

This scenario is not possible. An even number of servers doesn't help =
you as a quorum in ZooKeeper is (N/2)+1. So, if you put 2 servers in =
each DC, a network partition would disable BOTH DCs. (4/2)+1 =3D=3D 3. =
So, the only option is to choose one of the DCs as the main DC and put =
an extra server there. This way you could lose the "minor" DC.

-Jordan

> On Mar 6, 2017, at 11:34 AM, Le Cyberian <lecyberian@gmail.com> wrote:
>=20
> Hi Guys,
>=20
> I would like to have Kafka Cluster which is dependent on Zookeeper =
like
> many other great projects out their. Kafka would have 4 nodes as its
> cluster since their having even number is not a problem because it =
does
> leader election based its config it keeps in zookeeper.
>=20
> My scenario is having two server rooms on different floors having =
fiber
> connectivity with each other so network latency / lag is almost like a
> local connection.
>=20
> However, I would like to implement zookeeper cluster between both of =
them
> for auto-failover / redundancy purposes. So if one server room is down
> other should work properly.
>=20
> For example: on a 5 node zookeeper cluster distributed on both of the
> server rooms with 3 in one and 2 in other would give me 2 node failure
> tolerance, However if the server room which has 3 servers is down then
> ensemble would be broken and split brain.
>=20
> Can you please suggest how to achieve this to have failover / =
redundancy
> between two server rooms or two locations lets say ?
>=20
> Is it possible to run 3 node cluster in each server room and have some =
sort
> of master-master between them ?
>=20
> Thank for your time and helping out in advance.
>=20
> Kind regards,
>=20
> Le