Return-Path: Delivered-To: apmail-hadoop-common-commits-archive@www.apache.org Received: (qmail 24782 invoked from network); 20 Nov 2009 18:29:38 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 20 Nov 2009 18:29:38 -0000 Received: (qmail 68531 invoked by uid 500); 20 Nov 2009 18:29:37 -0000 Delivered-To: apmail-hadoop-common-commits-archive@hadoop.apache.org Received: (qmail 68458 invoked by uid 500); 20 Nov 2009 18:29:36 -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 68449 invoked by uid 500); 20 Nov 2009 18:29:36 -0000 Delivered-To: apmail-hadoop-core-commits@hadoop.apache.org Received: (qmail 68446 invoked by uid 99); 20 Nov 2009 18:29:36 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 20 Nov 2009 18:29:36 +0000 X-ASF-Spam-Status: No, hits=-2.6 required=5.0 tests=AWL,BAYES_00 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; Fri, 20 Nov 2009 18:29:34 +0000 Received: from eos.apache.org (localhost [127.0.0.1]) by eos.apache.org (Postfix) with ESMTP id 359A217D18; Fri, 20 Nov 2009 18:29:14 +0000 (GMT) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Apache Wiki To: Apache Wiki Date: Fri, 20 Nov 2009 18:29:14 -0000 Message-ID: <20091120182914.24905.19426@eos.apache.org> Subject: =?utf-8?q?=5BHadoop_Wiki=5D_Trivial_Update_of_=22ZooKeeper/HBaseUseCases?= =?utf-8?q?=22_by_stack?= Dear Wiki user, You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for ch= ange notification. The "ZooKeeper/HBaseUseCases" page has been changed by stack. http://wiki.apache.org/hadoop/ZooKeeper/HBaseUseCases?action=3Ddiff&rev1=3D= 14&rev2=3D15 -------------------------------------------------- =3D=3D=3D root-region-server =3D=3D=3D This znode holds the location of the server hosting the root of all table= s in hbase. = - Idea is to hoist the whole region up into zk rather than have it out as a= fully-fledged hbase region; it has little info in it. - = =3D=3D=3D master =3D=3D=3D = - This is current master. If more than one master, they fight over who it = should be. They all try to grab this znode. + This is current master. If more than one master, they fight over who it = should be. They all try to grab this znode. When this node evaporates, ma= sters try to grab it again. Whoever wins picks up the master role. = =3D=3D=3D rs =3D=3D=3D = A directory in which there is a znode per hbase server (regionserver) par= ticipating in the cluster. They register themselves when they come on line= . They name of the znode is a random number, the regions' startcode, so ca= n tell if regionserver has been restarted (We should fix this so server nam= es are more descriptive). + = + If regionserver session in zk is lost, this znode evaporates. The region= server will get the disconnect message and shut itself down. Master will s= tart the clean up process gathering its write-ahead logs, splitting them an= d divvying the edits out per region so they are available when regions are = opened in new locations on other running regionservers. = =3D=3D=3D shutdown =3D=3D=3D If cluster is to shutdown.