Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@cassandra.apache.org
Received-SPF: pass (nike.apache.org: domain of teddyyyy123@gmail.com
 designates 209.85.213.172 as permitted sender)
MIME-Version: 1.0
Date: Wed, 19 Oct 2011 10:29:58 -0700
Message-ID: 
 <CAAnh3_-JYPRkUbAePUO-KEzQRT2LsXi_=haJMmSvnSYrTWDnKw@mail.gmail.com>
Subject: weird problem with performance
From: Yang <teddyyyy123@gmail.com>
To: user@cassandra.apache.org
Content-Type: text/plain; charset=ISO-8859-1

I'm using a cassandra version compiled from 1.0.0  github HEAD.

I have 3 nodes, A B and C,  on node A I run a client, which talks only
to B as the coordinator.

the performance is pretty good, a QUORUM read+write  takes < 10ms.

but then I shutdown C, quickly the performance starts to degrade, and
QUORUM read+write time steadily increase to about 300ms.

if I shutdown A and keep C, I observe the same effect.


I understand that "2 out of 3" is going to give you faster response
than "2 out of 2", but  the difference should not be that dramatic as
10ms vs 300ms.

any possible reasons for this?(or how to debug this?)

Thanks
Yang