From user-return-25356-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Thu Apr 5 16:23:01 2012 Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id EA7C992EF for ; Thu, 5 Apr 2012 16:23:00 +0000 (UTC) Received: (qmail 36935 invoked by uid 500); 5 Apr 2012 16:22:58 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 36903 invoked by uid 500); 5 Apr 2012 16:22:58 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 36895 invoked by uid 99); 5 Apr 2012 16:22:58 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 05 Apr 2012 16:22:58 +0000 X-ASF-Spam-Status: No, hits=1.5 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of zhiming.shim@gmail.com designates 209.85.213.172 as permitted sender) Received: from [209.85.213.172] (HELO mail-yx0-f172.google.com) (209.85.213.172) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 05 Apr 2012 16:22:50 +0000 Received: by yenm5 with SMTP id m5so886236yen.31 for ; Thu, 05 Apr 2012 09:22:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=V5hDV4gLNTL6hG5wkwMKvYehRCVa1l1ioHIeHGw3d10=; b=a9LtywfLZsxUCNnEiEl3LpJdospnYpMxV5h5GE90+nkEhrpo/Oul+FrHxVHZqh0Jih CqLD2K2PnqYD4DdIOsQyG2KNUjZq3cF/VH+CltxpX76SIdroSstiSiox3+hlzwZqMFLp LlaqGvGI8bQIhf4k1XEIHSo+J6RTYpNdycP6dH+vx8A+kyiM5vhFDhat45mD16gJ7tIf zZ6eTZ8p2cHUXPxtBVJcxP9HtvI/YFUYgdF5xZGw2WWofXlFhM03KSPBo2uMQe+mXFRs fh6t65AaL5vVh5QLLDvZH/I81Q11M6L6oM0Ytq9pkbwDoMzRcor6xhT/4PQsmWcSfpDF uVFg== MIME-Version: 1.0 Received: by 10.50.202.38 with SMTP id kf6mr2572892igc.30.1333642949248; Thu, 05 Apr 2012 09:22:29 -0700 (PDT) Received: by 10.42.75.70 with HTTP; Thu, 5 Apr 2012 09:22:29 -0700 (PDT) In-Reply-To: <641DA0D7-9C8D-4F64-8A18-A895936A200C@gmail.com> References: <641DA0D7-9C8D-4F64-8A18-A895936A200C@gmail.com> Date: Thu, 5 Apr 2012 12:22:29 -0400 Message-ID: Subject: Re: Will Cassandra balance load across replicas? From: zhiming shen To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary=f46d0447a1233f465404bcf0f2df --f46d0447a1233f465404bcf0f2df Content-Type: text/plain; charset=ISO-8859-1 Thanks for your reply. My question is about the impact of replication on load balancing. Say we have nodes ABCD... in the ring. ReplicationFactor is 3 so the data on A will also have replicas on B and C. If we are reading data own by A, and A is already very busy, will the requests be forwarded to B and C? How about update requests? Thanks, Zhiming On Thu, Apr 5, 2012 at 12:33 AM, Watanabe Maki wrote: > I assume you are talking about nodes, rather than replicas. > The data distribution over ring depends on Partitioner and Replica > placement strategy you use. > If you are using Random Partitioner and Simple Strategy, your data will be > automatically distributed over the nodes in the ring. > > maki > > > On 2012/04/05, at 12:31, zhiming shen wrote: > > > Hi, > > > > Can any one tell me whether Cassandra can do load balancing across > replicas? How to configure it for this purpose? Thanks very much. > > > > > > Best Regards, > > > > Zhiming > --f46d0447a1233f465404bcf0f2df Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Thanks for your reply. My question is about the impact of replication on lo= ad balancing. Say we have nodes ABCD... in the ring. ReplicationFactor is 3= so the data on A will also have replicas on B and C. If we are reading dat= a own by A, and A is already very busy, will the requests be forwarded to B= and C? How about update requests?


Thanks,


Zhiming

On Thu= , Apr 5, 2012 at 12:33 AM, Watanabe Maki <watanabe.maki@gmail.com> wrote= :
I assume you are talking = about nodes, rather than replicas.
The data distribution over ring depends on Partitioner and Replica placemen= t strategy you use.
If you are using Random Partitioner and Simple Strategy, your data will be = automatically distributed over the nodes in the ring.

maki


On 2012/04/05, at 12:31, zhiming shen <zhiming.shim@gmail.com> wrote:

> Hi,
>
> Can any one tell me whether Cassandra can do load balancing across rep= licas? How to configure it for this purpose? Thanks very much.
>
>
> Best Regards,
>
> Zhiming

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