Return-Path: Delivered-To: apmail-hadoop-mapreduce-user-archive@minotaur.apache.org Received: (qmail 56286 invoked from network); 8 Oct 2010 01:31:57 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 8 Oct 2010 01:31:57 -0000 Received: (qmail 979 invoked by uid 500); 8 Oct 2010 01:31:57 -0000 Delivered-To: apmail-hadoop-mapreduce-user-archive@hadoop.apache.org Received: (qmail 932 invoked by uid 500); 8 Oct 2010 01:31:57 -0000 Mailing-List: contact mapreduce-user-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: mapreduce-user@hadoop.apache.org Delivered-To: mailing list mapreduce-user@hadoop.apache.org Received: (qmail 924 invoked by uid 99); 8 Oct 2010 01:31:57 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 08 Oct 2010 01:31:57 +0000 X-ASF-Spam-Status: No, hits=0.6 required=10.0 tests=FREEMAIL_FROM,HK_RANDOM_ENVFROM,RCVD_IN_DNSWL_NONE,SPF_PASS,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of zjffdu@gmail.com designates 74.125.82.48 as permitted sender) Received: from [74.125.82.48] (HELO mail-ww0-f48.google.com) (74.125.82.48) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 08 Oct 2010 01:31:51 +0000 Received: by wwb34 with SMTP id 34so372793wwb.29 for ; Thu, 07 Oct 2010 18:31:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=FTAb4kfOWPVabqiJN4EEHpEysqGBn1PLy/tbpqMqE5c=; b=MyKFbnq0VX1dN/gvtbX3/pC+BbCtGVt5QxQAdJu+3GBMFVhU4r4rz0j6owJJaSotL4 p9O/i/gAkkJtlCDugmEE2jBpS729PmH1DBDlovxPis2UqqVmG1sdEjCeCmnNFrcyfHeW TwbRc62Yk08FQUnFQCpi0PHxH2frgSdhbUQ5I= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=NizE8C4iBNepKtT+NHVfgaCXzOs4Xqr6Cx4OnYKPGNmqmOf+9v//i2Okl9zxnO1GG4 U2QIwl/vME2RuqdvdSppJ9kHjHwuGN7OVdSHCnLKm89e5ZdRkIEuXLDSqC0qsJpod250 tRw5qrXsehOPpRD5Me0gzcF/CdRC7cG10+OOc= MIME-Version: 1.0 Received: by 10.216.233.234 with SMTP id p84mr1550862weq.38.1286501489800; Thu, 07 Oct 2010 18:31:29 -0700 (PDT) Received: by 10.216.175.70 with HTTP; Thu, 7 Oct 2010 18:31:29 -0700 (PDT) In-Reply-To: References: Date: Fri, 8 Oct 2010 09:31:29 +0800 Message-ID: Subject: Re: Hdfs Block Size From: Jeff Zhang To: mapreduce-user@hadoop.apache.org Content-Type: text/plain; charset=UTF-8 Yes, this relates with the native file system block size and disk block size, and can reduce the disk fragmentation. On Fri, Oct 8, 2010 at 2:03 AM, rakesh kothari wrote: > Is there a reason why block size should be set to some 2^N, for some integer > N ? Does it help with block defragmentation etc. ? > > Thanks, > -Rakesh > -- Best Regards Jeff Zhang