From common-commits-return-9433-apmail-hadoop-common-commits-archive=hadoop.apache.org@hadoop.apache.org Tue Aug 11 15:40:26 2009 Return-Path: Delivered-To: apmail-hadoop-common-commits-archive@www.apache.org Received: (qmail 39951 invoked from network); 11 Aug 2009 15:40:26 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 11 Aug 2009 15:40:26 -0000 Received: (qmail 61227 invoked by uid 500); 11 Aug 2009 15:40:33 -0000 Delivered-To: apmail-hadoop-common-commits-archive@hadoop.apache.org Received: (qmail 61182 invoked by uid 500); 11 Aug 2009 15:40:33 -0000 Mailing-List: contact common-commits-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: common-dev@hadoop.apache.org Delivered-To: mailing list common-commits@hadoop.apache.org Received: (qmail 61172 invoked by uid 500); 11 Aug 2009 15:40:33 -0000 Delivered-To: apmail-hadoop-core-commits@hadoop.apache.org Received: (qmail 61169 invoked by uid 99); 11 Aug 2009 15:40:33 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 11 Aug 2009 15:40:33 +0000 X-ASF-Spam-Status: No, hits=-2000.0 required=10.0 tests=ALL_TRUSTED X-Spam-Check-By: apache.org Received: from [140.211.11.130] (HELO eos.apache.org) (140.211.11.130) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 11 Aug 2009 15:40:29 +0000 Received: from eos.apache.org (localhost [127.0.0.1]) by eos.apache.org (Postfix) with ESMTP id B134D1112F for ; Tue, 11 Aug 2009 15:40:08 +0000 (GMT) Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Apache Wiki To: core-commits@hadoop.apache.org Date: Tue, 11 Aug 2009 15:40:08 -0000 Message-ID: <20090811154008.6644.86194@eos.apache.org> Subject: [Hadoop Wiki] Trivial Update of "HadoopIsNot" by SteveLoughran X-Virus-Checked: Checked by ClamAV on apache.org Dear Wiki user, You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification. The following page has been changed by SteveLoughran: http://wiki.apache.org/hadoop/HadoopIsNot The comment on the change is: fix the bullets ------------------------------------------------------------------------------ We see a lot of emails where people hear about Hadoop, and think it will be the silver bullet to solve all their application/datacentre problems. It is not. It solves some specific problems for some companies and organisations, but only after they have understood the technology and where it is appropriate. If you start using Hadoop in the belief it is a drop-in replacement for your database or SAN filesystem, you will be disappointed. - == Hadoop is not a substitute for a database == + == Apache Hadoop is not a substitute for a database == Databases are wonderful. Issue an SQL SELECT call against an indexed/tuned database and the response comes back in milliseconds. Want to change that data? SQL UPDATE and the change is in. Hadoop does not do this. @@ -43, +43 @@ There are some very high-end filesystems out there: GPFS, Lustre, which offer fantastic data availability and performance, usually by requiring high end hardware (SAN and infiniband networking, RAID storage). Hadoop HDFS cheats, delivering high local data access rates by running code near the data, instead of being fast at shipping the data remotely. Instead of using RAID controllers, it uses non-RAIDed storage across multiple machines. - * It is not (currently) Highly Available. The Namenode is a ["SPOF"]. + * It is not (currently) Highly Available. The Namenode is a ["SPOF"]. - * It does not (currently) offer real security. It is probably less secure than Sun's original NFS filesystem. + * It does not (currently) offer real security. It is probably less secure than Sun's original NFS filesystem. Because of these limitations, if you want a secure filesystem that is always available, HDFS is not yet there. You can run Hadoop MapReduce over other filesystems, however.