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From Rakesh Radhakrishnan <rake...@apache.org>
Subject Re: Sessions Expire due to Network partitioning in Zookeeper
Date Thu, 02 Mar 2017 02:18:30 GMT
Hi,

Could you please give few more details,

1) Could you tell me the status of Server C, is this lost connection to the
quorum and fails to join quorum continuously as B is the Leader ?

2) C3 is connected C. Please tell me the connection host string passed to
this client. Does it contains all three servers info "A:clientport,
B:clientport, C:clientport" ?

3) Please check all three servers and client C3 logs to see any
inconsistencies or exceptions.

4) ZooKeeper version used in your testing ?


Rakesh

On Wed, Mar 1, 2017 at 4:55 PM, Tharindu Kumara <zonik.hatkumara@gmail.com>
wrote:

> ​Recently, carried out a test to to find the behavior of clients when a
> client is partitioned from the ensemble.
>
> Here I used a ensemble of 3 zookeeper servers called A, B and C. And quorum
> was set up like below.
>
> A - Follower
> B - Leader
> C - Follower​
>
> A  <---> B <---> C
>    \____________/
>
> And 3 clients are connected to ensemble like below.
>
> C1 is connected A
> C2 is connected B
> C3 is connected C.
>
> I used iptables to remove the network link between B and C.
>
> command used: iptables -I INPUT -s 123.123.45.123 -j DROP
>
> After removing the link connections looks like below.
>
> A  <----> B         C
>    \____________/
>
> Simply there is no way to communicate from B to C and vice versa.
>
> Here What I noticed is that the client connected to Zookeeper Server "C",
> could not connect to the ensemble resulting a session expiration timeout.
>
> For this experiment I used tickTime of 3000ms and client session expiration
> timeout of 45000ms. And tested with different combinations also.
>
> Can someone please explain what is the root cause for this behavior?
>

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