Return-Path: X-Original-To: apmail-hadoop-common-user-archive@www.apache.org Delivered-To: apmail-hadoop-common-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 B56131059C for ; Mon, 15 Jul 2013 21:57:00 +0000 (UTC) Received: (qmail 23477 invoked by uid 500); 15 Jul 2013 21:56:56 -0000 Delivered-To: apmail-hadoop-common-user-archive@hadoop.apache.org Received: (qmail 23371 invoked by uid 500); 15 Jul 2013 21:56:56 -0000 Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@hadoop.apache.org Delivered-To: mailing list user@hadoop.apache.org Received: (qmail 23364 invoked by uid 99); 15 Jul 2013 21:56:56 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 15 Jul 2013 21:56:56 +0000 X-ASF-Spam-Status: No, hits=-0.7 required=5.0 tests=RCVD_IN_DNSWL_LOW X-Spam-Check-By: apache.org Received-SPF: error (nike.apache.org: local policy) Received: from [217.70.183.196] (HELO relay4-d.mail.gandi.net) (217.70.183.196) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 15 Jul 2013 21:56:48 +0000 Received: from mfilter4-d.gandi.net (mfilter4-d.gandi.net [217.70.178.134]) by relay4-d.mail.gandi.net (Postfix) with ESMTP id 3806E172092 for ; Mon, 15 Jul 2013 23:56:08 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at mfilter4-d.gandi.net Received: from relay4-d.mail.gandi.net ([217.70.183.196]) by mfilter4-d.gandi.net (mfilter4-d.gandi.net [10.0.15.180]) (amavisd-new, port 10024) with ESMTP id 3I38xfqlYCfc for ; Mon, 15 Jul 2013 23:56:06 +0200 (CEST) X-Originating-IP: 10.58.1.145 Received: from webmail.nanthrax.net (unknown [10.58.1.145]) (Authenticated sender: jb@nanthrax.net) by relay4-d.mail.gandi.net (Postfix) with ESMTPA id C6973172089 for ; Mon, 15 Jul 2013 23:56:06 +0200 (CEST) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 15 Jul 2013 23:56:06 +0200 From: jb@nanthrax.net To: Subject: Re: Running a single cluster in multiple datacenters In-Reply-To: References: Message-ID: X-Sender: jb@nanthrax.net User-Agent: Roundcube Webmail/0.7.2 X-Virus-Checked: Checked by ClamAV on apache.org Hi Niels, it's depend of the number of replicas and the Hadoop rack configuration (level). It's possible to have replicas on the two datacenters. What's the rack configuration that you plan ? You can implement your own one and define it using the topology.node.switch.mapping.impl property. Regards JB On 2013-07-15 23:49, Niels Basjes wrote: > Hi, > > Last week we had a discussion at work regarding setting up our new > Hadoop cluster(s). > One of the things that has changed is that the importance of the > Hadoop stack is growing so we want to be "more available". > > One of the points we talked about was setting up the cluster in such > a > way that the nodes are physically located in two separate datacenters > (on opposite sides of the same city) with a big network connection in > between. > > Were currently talking about a cluster in the 50 nodes range, but > that > will grow over time. > > The advantages I see: > - More CPU power available for jobs. > - The data is automatically copied between the datacenters as long as > we configure them to be different racks. > > The disadvantages I see: > - If the network goes out then one half is dead and the other half > will most likely go to safemode because the recovering of the missing > replicas will fill up the disks fast. > > What things should we consider also? > Has anyone any experience with such a setup? > Is it a good idea to do this? > > What are better options for us to consider? > > Thanks for any input.