Return-Path: Delivered-To: apmail-hadoop-core-commits-archive@www.apache.org Received: (qmail 91703 invoked from network); 4 Apr 2009 21:06:11 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 4 Apr 2009 21:06:11 -0000 Received: (qmail 28752 invoked by uid 500); 4 Apr 2009 21:06:10 -0000 Delivered-To: apmail-hadoop-core-commits-archive@hadoop.apache.org Received: (qmail 28671 invoked by uid 500); 4 Apr 2009 21:06:10 -0000 Mailing-List: contact core-commits-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: core-dev@hadoop.apache.org Delivered-To: mailing list core-commits@hadoop.apache.org Received: (qmail 28662 invoked by uid 99); 4 Apr 2009 21:06:10 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 04 Apr 2009 21:06:10 +0000 X-ASF-Spam-Status: No, hits=-2000.0 required=10.0 tests=ALL_TRUSTED X-Spam-Check-By: apache.org Received: from [192.87.106.226] (HELO aurora.apache.org) (192.87.106.226) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 04 Apr 2009 21:06:09 +0000 Received: from aurora.apache.org (localhost [127.0.0.1]) by aurora.apache.org (8.13.8+Sun/8.13.8) with ESMTP id n34L5mpr020922 for ; Sat, 4 Apr 2009 21:05:48 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: Sat, 04 Apr 2009 21:05:48 -0000 Message-ID: <20090404210548.20884.45274@aurora.apache.org> Subject: [Hadoop Wiki] Trivial Update of "Hbase/DesignOverview" by EvgenyRyabitskiy 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 EvgenyRyabitskiy: http://wiki.apache.org/hadoop/Hbase/DesignOverview ------------------------------------------------------------------------------ * Cluster initialization * Assigning/unassigning regions to/from H!RegionServers (unassigning is for load balance) - * Monitor the health of each H!RegionServer + * Monitor the health and load of each H!RegionServer * Changes to the table schema and handling table administrative functions == Cluster initialization == @@ -134, +134 @@ ==== Assigned region ==== - If region is assigned to some H!RegionServer it means that this region served by this server. While serving region H!RegionServer handles read/write requests to this region, caches last (not yet flushed) modifications in memcache and writes all changes to WAL but persistent reliable storage of regions is provided by HDFS. + If region is assigned to some H!RegionServer it means that this region served by this server. While serving region H!RegionServer handles read/write requests to this region, caches last (not yet flushed) modifications in Memcache and writes all changes to WAL but persistent reliable storage of regions is provided by HDFS. ==== The META Table ==== @@ -152, +152 @@ If HMaster detects a H!RegionServer is no longer reachable, it will split the H!RegionServer's write-ahead log so that there is now one write-ahead log for each region that the H!RegionServer was serving. After it has accomplished this, it will reassign the regions that were being served by the unreachable H!RegionServer. + If HMaster detects overloaded or low loaded H!RegionServer, it will unassign (close) some regions from most loaded H!RegionServer. Unassigned regions will be assigned to lowest loaded server. + === Changes to the table schema and handling table administrative functions === Table schema is set of tables and it's column families. HMaster can add and remove column families, turn on/off tables. If HMaster dies, the cluster will shut down, but it will be changed soon after integration with !ZooKeeper. See [:Hbase/ZookeeperIntegration: ZooKeeper Integration] - [[Anchor(hregionserv)]] == HRegionServer ==