Mailing-List: contact user-help@zookeeper.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@zookeeper.apache.org
Received-SPF: pass (nike.apache.org: domain of samoilov@gmail.com designates
 209.85.192.182 as permitted sender)
MIME-Version: 1.0
Date: Tue, 21 Oct 2014 12:03:50 -0700
Message-ID: 
 <CA+RaP1d9iisg277+VJjnueiGWtuR55MAP=SMqeGhvupAYZT26Q@mail.gmail.com>
Subject: cross DC setup - is it Ok for ZK?
From: Denis Samoilov <samoilov@gmail.com>
To: user@zookeeper.apache.org
Content-Type: multipart/alternative; boundary=047d7b5d25dee796b30505f37dbf

--047d7b5d25dee796b30505f37dbf
Content-Type: text/plain; charset=UTF-8

hi,

Could you please help to understand the following setup: we have two
datacenters and want to setup ZK cluster so it will use servers (ZK servers
not clients) in both: like 3 ZK servers in DC1 and 4 ZK servers in DC2. We
sometime do maintenance in one or other DC. So ZK will completely lose
replicas in one of the DC for several hours. E.g. if DC2 is under
maintenance ZK will have only 3 out of 7 nodes and these 3 nodes supposed
to receive writes.

The questions:
1) is it Ok for ZK to have such setup?
2) will ZK catch up after losing 4 Servers and getting them back in some
time? (this will be a majority actually :) )
3) what is right number of nodes, is 5 sufficient : 2 +  3?

Latency between DCs is pretty low (DCs are close to each other).


Thank you for any advice.

-Denis

--047d7b5d25dee796b30505f37dbf--