Return-Path: 
 <user-return-14747-apmail-hadoop-common-user-archive=hadoop.apache.org@hadoop.apache.org>
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 6475410A94
	for <apmail-hadoop-common-user-archive@www.apache.org>;
 Thu,  3 Apr 2014 11:11:21 +0000 (UTC)
Received: (qmail 96682 invoked by uid 500); 3 Apr 2014 11:11:12 -0000
Delivered-To: apmail-hadoop-common-user-archive@hadoop.apache.org
Received: (qmail 96454 invoked by uid 500); 3 Apr 2014 11:11:09 -0000
Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
List-Help: <mailto:user-help@hadoop.apache.org>
List-Unsubscribe: <mailto:user-unsubscribe@hadoop.apache.org>
List-Post: <mailto:user@hadoop.apache.org>
List-Id: <user.hadoop.apache.org>
Reply-To: user@hadoop.apache.org
Delivered-To: mailing list user@hadoop.apache.org
Received: (qmail 96439 invoked by uid 99); 3 Apr 2014 11:11:07 -0000
Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230)
    by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 03 Apr 2014 11:11:07 +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 raofengyun@gmail.com designates
 209.85.128.178 as permitted sender)
Received: from [209.85.128.178] (HELO mail-ve0-f178.google.com)
 (209.85.128.178)
    by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 03 Apr 2014 11:11:01 +0000
Received: by mail-ve0-f178.google.com with SMTP id jw12so133171veb.37
        for <user@hadoop.apache.org>; Thu, 03 Apr 2014 04:10:39 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20120113;
        h=mime-version:date:message-id:subject:from:to:content-type;
        bh=J7UllGu56q21Xv3UIlNYBjnN3RPO6MAOiLrykPXhGig=;
        b=YxBNyKM4MGNlDSrBSyXHbHh1rfqa1iMWfMdIhYTErYTbXPyRgd9V90Bg43s4GwZ44h
         znW5QNBPyNVPagWYOg/IVpSfks7HBH1lLN4YLj56KfNHPJRMSTOM9OsmNaiFuftje1LW
         7MRlff4PNW2A1+Z+fcu7cRwWvja/IFf1Ng4RgLp8LFZwsEuryCTi5GjdtPIdt5Fqcgn4
         FMD8SZk6pswJQpzDzmChRp4DgCp+CAtPA34XRYnJYvPI9+jpmVEpvxQYC76ZDti89EZh
         xGdquw3d7HSW+vVkDa0pO2+yPd8DOURuUSuVtAicrgzxQzeGf549EePXS6H3cdgpHhUY
         8QYA==
MIME-Version: 1.0
X-Received: by 10.220.92.135 with SMTP id r7mr2479184vcm.11.1396523439405;
 Thu, 03 Apr 2014 04:10:39 -0700 (PDT)
Received: by 10.220.232.68 with HTTP; Thu, 3 Apr 2014 04:10:39 -0700 (PDT)
Date: Thu, 3 Apr 2014 19:10:39 +0800
Message-ID: 
 <CAGSyEuArE5sXkJh9tjj=9VBqQuD3ULCvRJGsPtMfmNb+9vT63A@mail.gmail.com>
Subject: recommended block replication for small cluster
From: Fengyun RAO <raofengyun@gmail.com>
To: user@hadoop.apache.org
Content-Type: multipart/alternative; boundary=047d7b66f5fb86ed0f04f62173e4
X-Virus-Checked: Checked by ClamAV on apache.org

--047d7b66f5fb86ed0f04f62173e4
Content-Type: text/plain; charset=ISO-8859-1

I know the default replication is 3, which ensures reliability when 2 nodes
crash at the same time.

However, for a small cluster, e.g. 10~20 nodes, the possibility that 2
nodes crash at the same time is too small.

Can we simply set the replication to 2, or are there any other defects?

any information are appreciated!

--047d7b66f5fb86ed0f04f62173e4
Content-Type: text/html; charset=ISO-8859-1

<div dir="ltr">I know the default replication is 3, which ensures reliability when 2 nodes crash at the same time.<div><br></div><div>However, for a small cluster, e.g. 10~20 nodes, the possibility that 2 nodes crash at the same time is too small.</div>
<div><br></div><div>Can we simply set the replication to 2, or are there any other defects?</div><div><br></div><div>any information are appreciated!</div></div>

--047d7b66f5fb86ed0f04f62173e4--