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 ADB24FB8C for ; Mon, 29 Apr 2013 20:07:40 +0000 (UTC) Received: (qmail 69283 invoked by uid 500); 29 Apr 2013 20:07:37 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 69264 invoked by uid 500); 29 Apr 2013 20:07:37 -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 69255 invoked by uid 99); 29 Apr 2013 20:07:37 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 29 Apr 2013 20:07:37 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: local policy) Received: from [208.113.200.5] (HELO homiemail-a58.g.dreamhost.com) (208.113.200.5) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 29 Apr 2013 20:07:31 +0000 Received: from homiemail-a58.g.dreamhost.com (localhost [127.0.0.1]) by homiemail-a58.g.dreamhost.com (Postfix) with ESMTP id C690A7D806A for ; Mon, 29 Apr 2013 13:07:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=thelastpickle.com; h=from :content-type:message-id:mime-version:subject:date:references:to :in-reply-to; s=thelastpickle.com; bh=FuHEGBqvdbql/qlJnVtixq+yJg Y=; b=r2aD2oBtajOPk92Earx3nNlu6/QM/rN5ZLZN1VAG1WrEj4mAMWwxcJM+zm uBtg4RyoeK2Tmxvf16aVkKKxbTKWQLWbvfajNOqJ1WQg0gGPGp4DC7H7/gjoH92V 6qws/rthiTXA0V78Qys7t7cxf4iSnIaeKXxE+UMd+IZLk/EKo= Received: from [172.16.1.8] (unknown [203.86.207.101]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: aaron@thelastpickle.com) by homiemail-a58.g.dreamhost.com (Postfix) with ESMTPSA id 15FC77D806D for ; Mon, 29 Apr 2013 13:07:21 -0700 (PDT) From: aaron morton Content-Type: multipart/alternative; boundary="Apple-Mail=_52C665EB-F225-4CAB-A85A-EB00DDBD7C06" Message-Id: <0F4ACB1D-8090-4E29-84EA-4B00BE390811@thelastpickle.com> Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\)) Subject: Re: Inter-DC communication optimization Date: Tue, 30 Apr 2013 08:07:06 +1200 References: To: user@cassandra.apache.org In-Reply-To: X-Mailer: Apple Mail (2.1503) X-Virus-Checked: Checked by ClamAV on apache.org --Apple-Mail=_52C665EB-F225-4CAB-A85A-EB00DDBD7C06 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 Messages are sent to all replicas involved in there request at the same = time. All nodes in the cluster must be able to communicate to all other = nodes. The coordinator the client is talking to, the local coordinator, groups = messages (for one read/mutation) to be sent to remove data centres and = only sends a single message to one node in each remote DC. In each = remote DC the receiving node then acts as a remote coordinator which = forwards the messages to the other replicas. All replicas in any DC = (local and remotes) reply directly back to the local DC.=20 Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 29/04/2013, at 11:47 PM, Sergey Naumov wrote: > Hello. >=20 > I would like to know whether updates are propagated from local DC to = remote DCs simultaneously (so All-to-All network connections are = preferable) or Cassandra can somehow determine nearest DCs and send = updates only to them (so these nearest DCs have to propagate updates = further)? > Is there some optimizations for multiple DCs placed sequentially on a = single link like DC1 <-> DC2 <-> ... <-> DCn? >=20 > Thanks in advance, > Sergey Naumov. --Apple-Mail=_52C665EB-F225-4CAB-A85A-EB00DDBD7C06 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=iso-8859-1
http://www.thelastpickle.com

On 29/04/2013, at 11:47 PM, Sergey Naumov <sknaumov@gmail.com> = wrote:

Hello.

I would like to know whether = updates are propagated from local DC to remote DCs simultaneously (so = All-to-All network connections are preferable) or Cassandra can somehow = determine nearest DCs and send updates only to them (so these nearest = DCs have to propagate updates further)?
Is there some optimizations for multiple DCs placed sequentially = on a single link like DC1 <-> DC2 <-> ... <-> = DCn?

Thanks in advance,
Sergey Naumov.

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