Author: suresh
Date: Thu Oct 20 00:29:12 2011
New Revision: 1186579
URL: http://svn.apache.org/viewvc?rev=1186579&view=rev
Log:
HDFS-2471. Add documentation for HDFS federation feature. Contributed by Suresh Srinivas.
Added:
hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/Federation.apt.vm
hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/
hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/federation-background.gif
(with props)
hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/federation.gif
(with props)
Modified:
hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/ClusterSetup.apt.vm
hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/index.apt.vm
Modified: hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/ClusterSetup.apt.vm
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/ClusterSetup.apt.vm?rev=1186579&r1=1186578&r2=1186579&view=diff
==============================================================================
--- hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/ClusterSetup.apt.vm
(original)
+++ hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/ClusterSetup.apt.vm
Thu Oct 20 00:29:12 2011
@@ -394,19 +394,19 @@ Hadoop MapReduce Next Generation - Clust
Format a new distributed filesystem:
----
- $ $HADOOP_HDFS_HOME/bin/hdfs namenode -format <cluster_name>
+ $ $HADOOP_PREFIX_HOME/bin/hdfs namenode -format <cluster_name>
----
Start the HDFS with the following command, run on the designated NameNode:
----
- $ $HADOOP_HDFS_HOME/bin/hdfs start namenode --config $HADOOP_CONF_DIR
+ $ $HADOOP_PREFIX_HOME/bin/hdfs start namenode --config $HADOOP_CONF_DIR
----
Run a script to start DataNodes on all slaves:
----
- $ $HADOOP_HDFS_HOME/bin/hdfs start datanode --config $HADOOP_CONF_DIR
+ $ $HADOOP_PREFIX_HOME/bin/hdfs start datanode --config $HADOOP_CONF_DIR
----
Start the YARN with the following command, run on the designated
@@ -435,13 +435,13 @@ Hadoop MapReduce Next Generation - Clust
NameNode:
----
- $ $HADOOP_HDFS_HOME/bin/hdfs stop namenode --config $HADOOP_CONF_DIR
+ $ $HADOOP_PREFIX_HOME/bin/hdfs stop namenode --config $HADOOP_CONF_DIR
----
Run a script to stop DataNodes on all slaves:
----
- $ $HADOOP_HDFS_HOME/bin/hdfs stop datanode --config $HADOOP_CONF_DIR
+ $ $HADOOP_PREFIX_HOME/bin/hdfs stop datanode --config $HADOOP_CONF_DIR
----
Stop the ResourceManager with the following command, run on the designated
@@ -910,21 +910,21 @@ KVNO Timestamp Principal
Format a new distributed filesystem as <hdfs>:
----
-[hdfs]$ $HADOOP_HDFS_HOME/bin/hdfs namenode -format <cluster_name>
+[hdfs]$ $HADOOP_PREFIX_HOME/bin/hdfs namenode -format <cluster_name>
----
Start the HDFS with the following command, run on the designated NameNode
as <hdfs>:
----
-[hdfs]$ $HADOOP_HDFS_HOME/bin/hdfs start namenode --config $HADOOP_CONF_DIR
+[hdfs]$ $HADOOP_PREFIX_HOME/bin/hdfs start namenode --config $HADOOP_CONF_DIR
----
Run a script to start DataNodes on all slaves as <root> with a special
environment variable <<<HADOOP_SECURE_DN_USER>>> set to <hdfs>:
----
-[root]$ HADOOP_SECURE_DN_USER=hdfs $HADOOP_HDFS_HOME/bin/hdfs start datanode --config $HADOOP_CONF_DIR
+[root]$ HADOOP_SECURE_DN_USER=hdfs $HADOOP_PREFIX_HOME/bin/hdfs start datanode --config $HADOOP_CONF_DIR
----
Start the YARN with the following command, run on the designated
@@ -953,13 +953,13 @@ KVNO Timestamp Principal
as <hdfs>:
----
-[hdfs]$ $HADOOP_HDFS_HOME/bin/hdfs stop namenode --config $HADOOP_CONF_DIR
+[hdfs]$ $HADOOP_PREFIX_HOME/bin/hdfs stop namenode --config $HADOOP_CONF_DIR
----
Run a script to stop DataNodes on all slaves as <root>:
----
-[root]$ $HADOOP_HDFS_HOME/bin/hdfs stop datanode --config $HADOOP_CONF_DIR
+[root]$ $HADOOP_PREFIX_HOME/bin/hdfs stop datanode --config $HADOOP_CONF_DIR
----
Stop the ResourceManager with the following command, run on the designated
@@ -998,4 +998,4 @@ KVNO Timestamp Principal
| | | Default HTTP port is 19888. |
*-------------------------+-------------------------+------------------------+
-
\ No newline at end of file
+
Added: hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/Federation.apt.vm
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/Federation.apt.vm?rev=1186579&view=auto
==============================================================================
--- hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/Federation.apt.vm
(added)
+++ hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/Federation.apt.vm
Thu Oct 20 00:29:12 2011
@@ -0,0 +1,343 @@
+
+~~ Licensed under the Apache License, Version 2.0 (the "License");
+~~ you may not use this file except in compliance with the License.
+~~ You may obtain a copy of the License at
+~~
+~~ http://www.apache.org/licenses/LICENSE-2.0
+~~
+~~ Unless required by applicable law or agreed to in writing, software
+~~ distributed under the License is distributed on an "AS IS" BASIS,
+~~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+~~ See the License for the specific language governing permissions and
+~~ limitations under the License. See accompanying LICENSE file.
+
+ ---
+ Hadoop Map Reduce Next Generation-${project.version} - Cluster Setup
+ ---
+ ---
+ ${maven.build.timestamp}
+
+HDFS Federation
+
+ \[ {{{./index.html}Go Back}} \]
+
+%{toc|section=1|fromDepth=0}
+
+ This guide provides an overview of the HDFS Federation feature and
+ how to configure and manage the federated cluster.
+
+* {Background}
+
+[./federation-background.gif] HDFS Layers
+
+ HDFS has two main layers:
+
+ * <<Namespace>>
+
+ * Consists of directories, files and blocks
+
+ * It supports all the namespace related file system operations such as
+ create, delete, modify and list files and directories.
+
+ * <<Block Storage Service>> has two parts
+
+ * Block Management (which is done in Namenode)
+
+ * Provides datanode cluster membership by handling registrations, and
+ periodic heart beats.
+
+ * Processes block reports and maintains location of blocks.
+
+ * Supports block related operations such as create, delete, modify and
+ get block location.
+
+ * Manages replica placement and replication of a block for under
+ replicated blocks and deletes blocks that are over replicated.
+
+ * Storage - is provided by datanodes by storing blocks on the local file
+ system and allows read/write access.
+
+ The current HDFS architecture allows only a single namespace for the
+ entire cluster. A single Namenode manages this namespace. HDFS
+ Federation addresses limitation of current architecture by adding
+ support multiple Namenodes/namespaces to HDFS file system.
+
+* {HDFS Federation}
+
+ In order to scale the name service horizontally, federation uses multiple
+ independent Namenodes/namespaces. The Namenodes are federated, that is, the
+ Namenodes are independent and donât require coordination with each other.
+ The datanodes are used as common storage for blocks by all the Namenodes.
+ Each datanode registers with all the Namenodes in the cluster. Datanodes
+ send periodic heartbeats and block reports and handles commands from the
+ Namenodes.
+
+[./federation.gif] HDFS Federation Architecture
+
+
+ <<Block Pool>>
+
+ A Block Pool is a set of blocks that belong to a single namespace.
+ Datanodes store blocks for all the block pools in the cluster.
+ It is managed independently of other block pools. This allows a namespace
+ to generate Block IDs for new blocks without the need for coordination
+ with the other namespaces. The failure of a Namenode does not prevent
+ the datanode from serving other Namenodes in the cluster.
+
+ A Namespace and its block pool together are called Namespace Volume.
+ It is a self-contained unit of management. When a Namenode/namespace
+ is deleted, the corresponding block pool at the datanodes is deleted.
+ Each namespace volume is upgraded as a unit, during cluster upgrade.
+
+ <<ClusterID>>
+
+ A new identifier <<ClusterID>> is added to identify all the nodes in
+ the cluster. When a Namenode is formatted, this identifier is provided
+ or auto generated. This ID should be used for formatting the other
+ Namenodes into the cluster.
+
+** Key Benefits
+
+ * Namespace Scalability - HDFS cluster storage scales horizontally but
+ the namespace does not. Large deployments or deployments using lot
+ of small files benefit from scaling the namespace by adding more
+ Namenodes to the cluster
+
+ * Performance - File system operation throughput is currently limited
+ by a single Namenode. Adding more Namenodes to the cluster scales the
+ file system read/write operations throughput.
+
+ * Isolation - A single Namenode offers no isolation in multi user
+ environment. An experimental application can overload the Namenode
+ and slow down production critical applications. With multiple Namenodes,
+ different categories of applications and users can be isolated to
+ different namespaces.
+
+* {Federation Configuration}
+
+ Federation configuration is <<backward compatible>> and allows existing
+ single Namenode configuration to work without any change. The new
+ configuration is designed such that all the nodes in the cluster have
+ same configuration without the need for deploying different configuration
+ based on the type of the node in the cluster.
+
+ A new abstraction called <<<NameServiceID>>> is added with
+ federation. The Namenode and its corresponding secondary/backup/checkpointer
+ nodes belong to this. To support single configuration file, the Namenode and
+ secondary/backup/checkpointer configuration parameters are suffixed with
+ <<<NameServiceID>>> and are added to the same configuration file.
+
+
+** Configuration:
+
+ <<Step 1>>: Add the following parameters to your configuration:
+ <<<dfs.federation.nameservices>>>: Configure with list of comma separated
+ NameServiceIDs. This will be used by Datanodes to determine all the
+ Namenodes in the cluster.
+
+ <<Step 2>>: For each Namenode and Secondary Namenode/BackupNode/Checkpointer
+ add the following configuration suffixed with the corresponding
+ <<<NameServiceID>>> into the common configuration file.
+
+*---------------------+--------------------------------------------+
+|| Daemon || Configuration Parameter |
+*---------------------+--------------------------------------------+
+| Namenode | <<<dfs.namenode.rpc-address>>> |
+| | <<<dfs.namenode.servicerpc-address>>> |
+| | <<<dfs.namenode.http-address>>> |
+| | <<<dfs.namenode.https-address>>> |
+| | <<<dfs.namenode.keytab.file>>> |
+| | <<<dfs.namenode.name.dir>>> |
+| | <<<dfs.namenode.edits.dir>>> |
+| | <<<dfs.namenode.checkpoint.dir>>> |
+| | <<<dfs.namenode.checkpoint.edits.dir>>> |
+*---------------------+--------------------------------------------+
+| Secondary Namenode | <<<dfs.namenode.secondary.http-address>>> |
+| | <<<dfs.secondary.namenode.keytab.file>>> |
+*---------------------+--------------------------------------------+
+| BackupNode | <<<dfs.namenode.backup.address>>> |
+| | <<<dfs.secondary.namenode.keytab.file>>> |
+*---------------------+--------------------------------------------+
+
+ Here is an example configuration with two namenodes:
+
+----
+<configuration>
+ <property>
+ <name>dfs.federation.nameservices</name>
+ <value>ns1,ns2</value>
+ </property>
+ <property>
+ <name>dfs.namenode.rpc-address.ns1</name>
+ <value>hdfs://nn-host1:rpc-port</value>
+ </property>
+ <property>
+ <name>dfs.namenode.http-address.ns1</name>
+ <value>nn-host1:http-port</value>
+ </property>
+ <property>
+ <name>dfs.namenode.secondaryhttp-address.ns1</name>
+ <value>snn-host1:http-port</value>
+ </property>
+ <property>
+ <name>dfs.namenode.rpc-address.ns2</name>
+ <value>hdfs://nn-host2:rpc-port</value>
+ </property>
+ <property>
+ <name>dfs.namenode.http-address.ns2</name>
+ <value>nn-host2:http-port</value>
+ </property>
+ <property>
+ <name>dfs.namenode.secondaryhttp-address.ns2</name>
+ <value>snn-host2:http-port</value>
+ </property>
+
+ .... Other common configuration ...
+</configuration>
+----
+
+** Formatting Namenodes
+
+ <<Step 1>>: Format a namenode using the following command:
+
+----
+> $HADOOP_PREFIX_HOME/bin/hdfs namenode -format [-clusterId <cluster_id>]
+----
+ Choose a unique cluster_id, which will not conflict other clusters in
+ your environment. If it is not provided, then a unique ClusterID is
+ auto generated.
+
+ <<Step 2>>: Format additional namenode using the following command:
+
+----
+> $HADOOP_PREFIX_HOME/bin/hdfs namenode -format -clusterId <cluster_id>
+----
+ Note that the cluster_id in step 2 must be same as that of the
+ cluster_id in step 1. If they are different, the additional Namenodes
+ will not be part of the federated cluster.
+
+** Upgrading from older release to 0.23 and configuring federation
+
+ Older releases supported a single Namenode. Here are the steps enable
+ federation:
+
+ Step 1: Upgrade the cluster to newer release. During upgrade you can
+ provide a ClusterID as follows:
+
+----
+> $HADOOP_PREFIX_HOME/bin/hdfs start namenode --config $HADOOP_CONF_DIR -upgrade -clusterId
<cluster_ID>
+----
+ If ClusterID is not provided, it is auto generated.
+
+** Adding a new Namenode to an existing HDFS cluster
+
+ Follow the following steps:
+
+ * Add configuration parameter <<<dfs.federation.nameservices>>> to
+ the configuration.
+
+ * Update the configuration with NameServiceID suffix. Configuration
+ key names have changed post release 0.20. You must use new configuration
+ parameter names, for federation.
+
+ * Add new Namenode related config to the configuration files.
+
+ * Propagate the configuration file to the all the nodes in the cluster.
+
+ * Start the new Namenode, Secondary/Backup.
+
+ * Refresh the datanodes to pickup the newly added Namenode by running
+ the following command:
+
+----
+> $HADOOP_PREFIX_HOME/bin/hdfs dfadmin -refreshNameNode <datanode_host_name>:<datanode_rpc_port>
+----
+
+ * The above command must be run against all the datanodes in the cluster.
+
+* {Managing the cluster}
+
+** Starting and stopping cluster
+
+ To start the cluster run the following command:
+
+----
+> $HADOOP_PREFIX_HOME/bin/start-dfs.sh
+----
+
+ To start the cluster run the following command:
+
+----
+> $HADOOP_PREFIX_HOME/bin/stop-dfs.sh
+----
+
+ These commands can be run from any node where the HDFS configuration is
+ available. The command uses configuration to determine the Namenodes
+ in the cluster and starts the Namenode process on those nodes. The
+ datanodes are started on nodes specified in the <<<slaves>>> file. The
+ script can be used as reference for building your own scripts for
+ starting and stopping the cluster.
+
+** Balancer
+
+ Balancer has been changed to work with multiple Namenodes in the cluster to
+ balance the cluster. Balancer can be run using the command:
+
+----
+"$HADOOP_PREFIX"/bin/hadoop-daemon.sh --config $HADOOP_CONF_DIR --script "$bin"/hdfs start
balancer [-policy <policy>]
+----
+
+ Policy could be:
+
+ * <<<node>>> - this is the <default> policy. This balances the
storage at
+ the datanode level. This is similar to balancing policy from prior releases.
+
+ * <<<blockpool>>> - this balances the storage at the block pool level.
+ Balancing at block pool level balances storage at the datanode level also.
+
+ Note that Balander only balances the data and does not balance the namespace.
+
+** Decommissioning
+
+ Decommissioning is similar to prior releases. The nodes that need to be
+ decommissioning are added to the exclude file at all the Namenode. Each
+ Namenode decommissions its Block Pool. When all the Namenodes finish
+ decommissioning a datanode, the datanode is considered to be decommissioned.
+
+ <<Step 1>>: To distributed an exclude file to all the Namenodes, use the
+ following command:
+
+----
+"$HADOOP_PREFIX"/bin/distributed-exclude.sh <exclude_file>
+----
+
+ <<Step 2>>: Refresh all the Namenodes to pick up the new exclude file.
+
+----
+"$HADOOP_PREFIX"/bin/refresh-namenodes.sh
+----
+
+ The above command uses HDFS configuration to determine the Namenodes
+ configured in the cluster and refreshes all the Namenodes to pick up
+ the new exclude file.
+
+** Cluster Web Console
+
+ Similar to Namenode status web page, a Cluster Web Console is added in
+ federation to monitor the federated cluster at
+ <<<http://<any_nn_host:port>/dfsclusterhealth.jsp>>>.
+ Any Namenode in the cluster can be used to access this web page.
+
+ The web page provides the following information:
+
+ * Cluster summary that shows number of files, number of blocks and
+ total configured storage capacity, available and used storage information
+ for the entire cluster.
+
+ * Provides list of Namenodes and summary that includes number of files,
+ blocks, missing blocks, number of live and dead data nodes for each
+ Namenode. It also provides a link to conveniently access Namenode web UI.
+
+ * It also provides decommissioning status of datanodes.
+
+
Modified: hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/index.apt.vm
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/index.apt.vm?rev=1186579&r1=1186578&r2=1186579&view=diff
==============================================================================
--- hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/index.apt.vm
(original)
+++ hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/index.apt.vm
Thu Oct 20 00:29:12 2011
@@ -49,3 +49,5 @@ Hadoop MapReduce Next Generation
* {{{./CapacityScheduler.html}Capacity Scheduler}}
+ * {{{./Federation.html}HDFS Federation feature description, configuration and management}}
+
Added: hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/federation-background.gif
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/federation-background.gif?rev=1186579&view=auto
==============================================================================
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Propchange: hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/federation-background.gif
------------------------------------------------------------------------------
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Added: hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/federation.gif
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-0.23/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/resources/federation.gif?rev=1186579&view=auto
==============================================================================
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------------------------------------------------------------------------------
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|