From hdfs-issues-return-8239-apmail-hadoop-hdfs-issues-archive=hadoop.apache.org@hadoop.apache.org Mon Apr 12 11:59:03 2010 Return-Path: Delivered-To: apmail-hadoop-hdfs-issues-archive@minotaur.apache.org Received: (qmail 226 invoked from network); 12 Apr 2010 11:59:03 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 12 Apr 2010 11:59:03 -0000 Received: (qmail 16909 invoked by uid 500); 12 Apr 2010 11:59:03 -0000 Delivered-To: apmail-hadoop-hdfs-issues-archive@hadoop.apache.org Received: (qmail 16876 invoked by uid 500); 12 Apr 2010 11:59:03 -0000 Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: hdfs-issues@hadoop.apache.org Delivered-To: mailing list hdfs-issues@hadoop.apache.org Received: (qmail 16868 invoked by uid 99); 12 Apr 2010 11:59:03 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 12 Apr 2010 11:59:03 +0000 X-ASF-Spam-Status: No, hits=-1266.4 required=10.0 tests=ALL_TRUSTED,AWL X-Spam-Check-By: apache.org Received: from [140.211.11.22] (HELO thor.apache.org) (140.211.11.22) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 12 Apr 2010 11:59:02 +0000 Received: from thor (localhost [127.0.0.1]) by thor.apache.org (8.13.8+Sun/8.13.8) with ESMTP id o3CBwgf3025182 for ; Mon, 12 Apr 2010 07:58:42 -0400 (EDT) Message-ID: <383776.21291271073522134.JavaMail.jira@thor> Date: Mon, 12 Apr 2010 07:58:42 -0400 (EDT) From: "Brian Bockelman (JIRA)" To: hdfs-issues@hadoop.apache.org Subject: [jira] Commented: (HDFS-1094) Intelligent block placement policy to decrease probability of block loss In-Reply-To: <24967451.18401271056063147.JavaMail.jira@thor> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 [ https://issues.apache.org/jira/browse/HDFS-1094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12855935#action_12855935 ] Brian Bockelman commented on HDFS-1094: --------------------------------------- Hey Dhruba, How does this change the probability? Are you saying that P(rack r and rack r+1 fails) < P(rack i and rack j, i!=j) fails? Can you sketch out mathematically how this decreases the probability of failure? Brian > Intelligent block placement policy to decrease probability of block loss > ------------------------------------------------------------------------ > > Key: HDFS-1094 > URL: https://issues.apache.org/jira/browse/HDFS-1094 > Project: Hadoop HDFS > Issue Type: Improvement > Components: name-node > Reporter: dhruba borthakur > Assignee: dhruba borthakur > > The current HDFS implementation specifies that the first replica is local and the other two replicas are on any two random nodes on a random remote rack. This means that if any three datanodes die together, then there is a non-trivial probability of losing at least one block in the cluster. This JIRA is to discuss if there is a better algorithm that can lower probability of losing a block. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: https://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira