From user-return-9726-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Thu Oct 07 02:27:14 2010 Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 6575 invoked from network); 7 Oct 2010 02:27:14 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 7 Oct 2010 02:27:14 -0000 Received: (qmail 27805 invoked by uid 500); 7 Oct 2010 02:27:12 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 27778 invoked by uid 500); 7 Oct 2010 02:27:12 -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 27770 invoked by uid 99); 7 Oct 2010 02:27:12 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 07 Oct 2010 02:27:12 +0000 X-ASF-Spam-Status: No, hits=0.0 required=10.0 tests=FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of jbellis@gmail.com designates 209.85.212.44 as permitted sender) Received: from [209.85.212.44] (HELO mail-vw0-f44.google.com) (209.85.212.44) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 07 Oct 2010 02:27:07 +0000 Received: by vws10 with SMTP id 10so168469vws.31 for ; Wed, 06 Oct 2010 19:26:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=LksXs9isGIII20v779bw/6+J/s7aoIQX8YMUoTzRNTU=; b=cSNxV3w9Z7aMhV8IMHUIKYs69CGY6v1E5E/h29trJBAdtYEfvu7TDe4roYxu5jTrMD Fzkej+FvLfV+ivEEIaniFyc06ZPcFLq3SlaUt1c0zbg360/p/e6x6WZmDCIUAyJHtGr/ Q9IM99/E9hXcTWtT2uPuANS+hYB8Wt8mKhkwk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=Oa9URGVqgYtnuchzymNalR4+WOhT6+GNczW2ts2ucPQuOOt3uhnP623E2ysk9Dysap 4y2PNODX+WjZZ7kLXtH7gujNngVprBJExyxR0QIdSEpnf4WO6H7G5i5Ic/bwQZ7EFJMP Es8c75JIq/eauiZgGLN4l5zRKn79v+OfZybt0= MIME-Version: 1.0 Received: by 10.220.168.141 with SMTP id u13mr52299vcy.256.1286418406251; Wed, 06 Oct 2010 19:26:46 -0700 (PDT) Received: by 10.220.176.131 with HTTP; Wed, 6 Oct 2010 19:26:46 -0700 (PDT) In-Reply-To: References: Date: Wed, 6 Oct 2010 21:26:46 -0500 Message-ID: Subject: Re: How is data propagated From: Jonathan Ellis To: user Content-Type: text/plain; charset=ISO-8859-1 the former, but also see http://issues.apache.org/jira/browse/CASSANDRA-1530 On Wed, Oct 6, 2010 at 9:22 PM, MK wrote: > Say I have a cluster of N nodes and I have started all the nodes with > a replication factor of N. So effectively all data is being mirrored > everywhere. > > Now, when I write to a node, how does this data get propagated to the > remaining N-1 nodes. > > 1) Does this one origin node do N-1 network operations to send the data off > 2) or does the data replication happen in some special distributed > manner (say origin node writes it to its neigbhors who further write > it to their neighbors and so on ) > > I need to know this because I am thinking about what happens when say > the link between two datacenters is down. > > Regards, > MK > -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com