From hdfs-issues-return-21829-apmail-hadoop-hdfs-issues-archive=hadoop.apache.org@hadoop.apache.org Fri Jul 1 23:39:50 2011 Return-Path: X-Original-To: apmail-hadoop-hdfs-issues-archive@minotaur.apache.org Delivered-To: apmail-hadoop-hdfs-issues-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 7587945D3 for ; Fri, 1 Jul 2011 23:39:50 +0000 (UTC) Received: (qmail 77376 invoked by uid 500); 1 Jul 2011 23:39:50 -0000 Delivered-To: apmail-hadoop-hdfs-issues-archive@hadoop.apache.org Received: (qmail 77248 invoked by uid 500); 1 Jul 2011 23:39:49 -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 77238 invoked by uid 99); 1 Jul 2011 23:39:49 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 01 Jul 2011 23:39:49 +0000 X-ASF-Spam-Status: No, hits=-2000.0 required=5.0 tests=ALL_TRUSTED,T_RP_MATCHES_RCVD X-Spam-Check-By: apache.org Received: from [140.211.11.116] (HELO hel.zones.apache.org) (140.211.11.116) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 01 Jul 2011 23:39:48 +0000 Received: from hel.zones.apache.org (hel.zones.apache.org [140.211.11.116]) by hel.zones.apache.org (Postfix) with ESMTP id 666CF43FC62 for ; Fri, 1 Jul 2011 23:39:28 +0000 (UTC) Date: Fri, 1 Jul 2011 23:39:28 +0000 (UTC) From: "dhruba borthakur (JIRA)" To: hdfs-issues@hadoop.apache.org Message-ID: <854176385.10129.1309563568416.JavaMail.tomcat@hel.zones.apache.org> Subject: [jira] [Commented] (HDFS-395) DFS Scalability: Incremental block reports 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-395?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13058869#comment-13058869 ] dhruba borthakur commented on HDFS-395: --------------------------------------- I agree with Scott. It would be nice to make the deletions/renames occur async but somehow handle the race condition in the code. > DFS Scalability: Incremental block reports > ------------------------------------------ > > Key: HDFS-395 > URL: https://issues.apache.org/jira/browse/HDFS-395 > Project: Hadoop HDFS > Issue Type: Sub-task > Reporter: dhruba borthakur > Assignee: dhruba borthakur > Attachments: blockReportPeriod.patch, explicitDeleteAcks.patch > > > I have a cluster that has 1800 datanodes. Each datanode has around 50000 blocks and sends a block report to the namenode once every hour. This means that the namenode processes a block report once every 2 seconds. Each block report contains all blocks that the datanode currently hosts. This makes the namenode compare a huge number of blocks that practically remains the same between two consecutive reports. This wastes CPU on the namenode. > The problem becomes worse when the number of datanodes increases. > One proposal is to make succeeding block reports (after a successful send of a full block report) be incremental. This will make the namenode process only those blocks that were added/deleted in the last period. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira