##### General

- Overview
- Single Node Setup
- Cluster Setup
- Commands Reference
- FileSystem Shell
- Compatibility Specification
- Downstream Developer's Guide
- Admin Compatibility Guide
- Interface Classification
- FileSystem Specification

##### Common

- CLI Mini Cluster
- Native Libraries
- Proxy User
- Rack Awareness
- Secure Mode
- Service Level Authorization
- HTTP Authentication
- Credential Provider API
- Hadoop KMS
- Tracing
- Unix Shell Guide

##### HDFS

- Architecture
- User Guide
- Commands Reference
- NameNode HA With QJM
- NameNode HA With NFS
- Observer NameNode
- Federation
- ViewFs
- ViewFsOverloadScheme
- Snapshots
- Edits Viewer
- Image Viewer
- Permissions and HDFS
- Quotas and HDFS
- libhdfs (C API)
- WebHDFS (REST API)
- HttpFS
- Short Circuit Local Reads
- Centralized Cache Management
- NFS Gateway
- Rolling Upgrade
- Extended Attributes
- Transparent Encryption
- Multihoming
- Storage Policies
- Memory Storage Support
- Synthetic Load Generator
- Erasure Coding
- Disk Balancer
- Upgrade Domain
- DataNode Admin
- Router Federation
- Provided Storage

##### MapReduce

- Tutorial
- Commands Reference
- Compatibility with 1.x
- Encrypted Shuffle
- Pluggable Shuffle/Sort
- Distributed Cache Deploy
- Support for YARN Shared Cache

##### MapReduce REST APIs

- MR Application Master
- MR History Server

##### YARN

- Architecture
- Commands Reference
- Capacity Scheduler
- Fair Scheduler
- ResourceManager Restart
- ResourceManager HA
- Resource Model
- Node Labels
- Node Attributes
- Web Application Proxy
- Timeline Server
- Timeline Service V.2
- Writing YARN Applications
- YARN Application Security
- NodeManager
- Running Applications in Docker Containers
- Using CGroups
- Secure Containers
- Registry
- Reservation System
- Graceful Decommission
- Opportunistic Containers
- YARN Federation
- Shared Cache
- Using GPU
- Using FPGA
- Placement Constraints
- YARN UI2

##### YARN REST APIs

- Introduction
- Resource Manager
- Node Manager
- Timeline Server
- Timeline Service V.2

##### YARN Service

- Overview
- QuickStart
- Concepts
- Yarn Service API
- Service Discovery
- System Services

##### Submarine

- Index
- QuickStart
- Examples

##### Hadoop Compatible File Systems

- Aliyun OSS
- Amazon S3
- Azure Blob Storage
- Azure Data Lake Storage
- OpenStack Swift

##### Auth

- Overview
- Examples
- Configuration
- Building

##### Tools

- Hadoop Streaming
- Hadoop Archives
- Hadoop Archive Logs
- DistCp
- GridMix
- Rumen
- Resource Estimator Service
- Scheduler Load Simulator
- Hadoop Benchmarking

##### Reference

- Changelog and Release Notes
- Java API docs
- Unix Shell API
- Metrics

##### Configuration

- core-default.xml
- hdfs-default.xml
- hdfs-rbf-default.xml
- mapred-default.xml
- yarn-default.xml
- kms-default.xml
- httpfs-default.xml
- Deprecated Properties

# Apache Hadoop Changelog

## Release 0.20.205.0 - 2011-10-06

### INCOMPATIBLE CHANGES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-630 | In DFSOutputStream.nextBlockOutputStream(), the client can exclude specific datanodes when locating the next block. | Major | hdfs-client, namenode | Ruyue Ma | Cosmin Lehene
HDFS-1554 | Append 0.20: New semantics for recoverLease | Major | . | Hairong Kuang | Hairong Kuang
HDFS-2202 | Changes to balancer bandwidth should not require datanode restart. | Major | balancer & mover, datanode | Eric Payne | Eric Payne

### NEW FEATURES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-200 | In HDFS, sync() not yet guarantees data available to the new readers | Blocker | . | Tsz Wo Nicholas Sze | dhruba borthakur
HDFS-1520 | HDFS 20 append: Lightweight NameNode operation to trigger lease recovery | Major | namenode | Hairong Kuang | Hairong Kuang
HADOOP-7594 | Support HTTP REST in HttpServer | Major | . | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
HADOOP-7119 | add Kerberos HTTP SPNEGO authentication support to Hadoop JT/NN/DN/TT web-consoles | Major | security | Alejandro Abdelnur | Alejandro Abdelnur
HADOOP-6889 | Make RPC to have an option to timeout | Major | ipc | Hairong Kuang | John George
MAPREDUCE-2777 | Backport MAPREDUCE-220 to Hadoop 20 security branch | Major | . | Jonathan Eagles | Amar Kamat

### IMPROVEMENTS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-826 | Allow a mechanism for an application to detect that datanode(s) have died in the write pipeline | Major | hdfs-client | dhruba borthakur | dhruba borthakur
HDFS-1054 | Remove unnecessary sleep after failure in nextBlockOutputStream | Major | hdfs-client | Todd Lipcon | Todd Lipcon
HDFS-1210 | DFSClient should log exception when block recovery fails | Trivial | hdfs-client | Todd Lipcon | Todd Lipcon
HDFS-1211 | 0.20 append: Block receiver should not log “rewind” packets at INFO level | Minor | datanode | Todd Lipcon | Todd Lipcon
HDFS-895 | Allow hflush/sync to occur in parallel with new writes to the file | Major | hdfs-client | dhruba borthakur | Todd Lipcon
HDFS-1555 | HDFS 20 append: Disallow pipeline recovery if a file is already being lease recovered | Major | . | Hairong Kuang | Hairong Kuang
HADOOP-7343 | backport HADOOP-7008 and HADOOP-7042 to branch-0.20-security | Minor | test | Thomas Graves | Thomas Graves
HADOOP-7432 | Back-port HADOOP-7110 to 0.20-security | Major | . | Sherry Chen | Sherry Chen
HADOOP-7314 | Add support for throwing UnknownHostException when a host doesn’t resolve | Major | . | Jeffrey Naisbitt | Jeffrey Naisbitt
MAPREDUCE-2494 | Make the distributed cache delete entires using LRU priority | Major | distributed-cache | Robert Joseph Evans | Robert Joseph Evans
MAPREDUCE-2729 | Reducers are always counted having “pending tasks” even if they can’t be scheduled yet because not enough of their mappers have completed | Major | . | Sherry Chen | Sherry Chen
HADOOP-7472 | RPC client should deal with the IP address changes | Minor | ipc | Kihwal Lee | Kihwal Lee
MAPREDUCE-2981 | Backport trunk fairscheduler to 0.20-security branch | Major | contrib/fair-share | Matei Zaharia | Matei Zaharia
HADOOP-7707 | improve config generator to allow users to specify proxy user, turn append on or off, turn webhdfs on or off | Major | conf | Arpit Gupta | Arpit Gupta
HADOOP-7720 | improve the hadoop-setup-conf.sh to read in the hbase user and setup the configs | Major | conf | Arpit Gupta | Arpit Gupta
HADOOP-7655 | provide a small validation script that smoke tests the installed cluster | Major | . | Arpit Gupta | Arpit Gupta

### BUG FIXES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-606 | ConcurrentModificationException in invalidateCorruptReplicas() | Major | namenode | Konstantin Shvachko | Konstantin Shvachko
HDFS-724 | Pipeline close hangs if one of the datanode is not responsive. | Blocker | datanode, hdfs-client | Tsz Wo Nicholas Sze | Hairong Kuang
HADOOP-6722 | NetUtils.connect should check that it hasn’t connected a socket to itself | Major | util | Todd Lipcon | Todd Lipcon
HDFS-142 | In 0.20, move blocks being written into a blocksBeingWritten directory | Blocker | . | Raghu Angadi | dhruba borthakur
HDFS-1141 | completeFile does not check lease ownership | Blocker | namenode | Todd Lipcon | Todd Lipcon
HDFS-1207 | 0.20-append: stallReplicationWork should be volatile | Major | namenode | Todd Lipcon | Todd Lipcon
HDFS-1204 | 0.20: Lease expiration should recover single files, not entire lease holder | Major | . | Todd Lipcon | sam rash
HDFS-1118 | DFSOutputStream socket leak when cannot connect to DataNode | Major | . | Zheng Shao | Zheng Shao
HDFS-1202 | DataBlockScanner throws NPE when updated before initialized | Major | datanode | Todd Lipcon | Todd Lipcon
HADOOP-6833 | IPC leaks call parameters when exceptions thrown | Blocker | . | Todd Lipcon | Todd Lipcon
HDFS-1346 | DFSClient receives out of order packet ack | Major | datanode, hdfs-client | Hairong Kuang | Hairong Kuang
HDFS-1164 | TestHdfsProxy is failing | Major | contrib/hdfsproxy | Eli Collins | Todd Lipcon
HDFS-988 | saveNamespace race can corrupt the edits log | Blocker | namenode | dhruba borthakur | Eli Collins
HDFS-1836 | Thousand of CLOSE_WAIT socket | Major | hdfs-client | Dennis Cheung | Bharath Mundlapudi
HADOOP-7400 | HdfsProxyTests fails when the -Dtest.build.dir and -Dbuild.test is set | Major | build | Giridharan Kesavan | Giridharan Kesavan
MAPREDUCE-2650 | back-port MAPREDUCE-2238 to 0.20-security | Major | . | Sherry Chen | Sherry Chen
MAPREDUCE-2324 | Job should fail if a reduce task can’t be scheduled anywhere | Major | . | Todd Lipcon | Robert Joseph Evans
MAPREDUCE-2187 | map tasks timeout during sorting | Major | . | Gianmarco De Francisci Morales | Anupam Seth
HDFS-2053 | Bug in INodeDirectory#computeContentSummary warning | Minor | namenode | Michael Noll | Michael Noll
HDFS-2117 | DiskChecker#mkdirsWithExistsAndPermissionCheck may return true even when the dir is not created | Minor | datanode | Eli Collins | Eli Collins
MAPREDUCE-2705 | tasks localized and launched serially by TaskLauncher - causing other tasks to be delayed | Major | tasktracker | Thomas Graves | Thomas Graves
HDFS-2190 | NN fails to start if it encounters an empty or malformed fstime file | Major | namenode | Aaron T. Myers | Aaron T. Myers
MAPREDUCE-2489 | Jobsplits with random hostnames can make the queue unusable | Major | jobtracker | Jeffrey Naisbitt | Jeffrey Naisbitt
HDFS-2259 | DN web-UI doesn’t work with paths that contain html | Minor | datanode | Eli Collins | Eli Collins
MAPREDUCE-2852 | Jira for YDH bug 2854624 | Major | tasktracker | Eli Collins | Kihwal Lee
HADOOP-7539 | merge hadoop archive goodness from trunk to .20 | Major | . | John George | John George
HADOOP-7596 | Enable jsvc to work with Hadoop RPM package | Major | build | Eric Yang | Eric Yang
HDFS-2309 | TestRenameWhileOpen fails in branch-0.20-security | Major | . | Jitendra Nath Pandey | Jitendra Nath Pandey
HDFS-2320 | Make merged protocol changes from 0.20-append to 0.20-security compatible with previous releases. | Major | datanode, hdfs-client, namenode | Suresh Srinivas | Suresh Srinivas
MAPREDUCE-2610 | Inconsistent API JobClient.getQueueAclsForCurrentUser | Major | client | Joep Rottinghuis | Joep Rottinghuis
MAPREDUCE-2915 | LinuxTaskController does not work when JniBasedUnixGroupsNetgroupMapping or JniBasedUnixGroupsMapping is enabled | Major | task-controller | Kihwal Lee | Kihwal Lee
HADOOP-7610 | /etc/profile.d does not exist on Debian | Major | scripts | Eric Yang | Eric Yang
HADOOP-7599 | Improve hadoop setup conf script to setup secure Hadoop cluster | Major | scripts | Eric Yang | Eric Yang
HADOOP-7626 | Allow overwrite of HADOOP_CLASSPATH and HADOOP_OPTS | Major | scripts | Eric Yang | Eric Yang
MAPREDUCE-2549 | Potential resource leaks in HadoopServer.java, RunOnHadoopWizard.java and Environment.java | Major | contrib/eclipse-plugin, contrib/streaming | Devaraj K | Devaraj K
HDFS-2328 | hftp throws NPE if security is not enabled on remote cluster | Critical | . | Daryn Sharp | Owen O’Malley
HDFS-1779 | After NameNode restart , Clients can not read partial files even after client invokes Sync. | Major | datanode, namenode | Uma Maheswara Rao G | Uma Maheswara Rao G
HDFS-2331 | Hdfs compilation fails | Major | hdfs-client | Abhijit Suresh Shingate | Abhijit Suresh Shingate
HDFS-2333 | HDFS-2284 introduced 2 findbugs warnings on trunk | Major | . | Ivan Kelly | Tsz Wo Nicholas Sze
HADOOP-7625 | TestDelegationToken is failing in 205 | Major | . | Owen O’Malley | Owen O’Malley
HADOOP-7637 | Fair scheduler configuration file is not bundled in RPM | Major | build | Eric Yang | Eric Yang
HADOOP-7631 | In mapred-site.xml, stream.tmpdir is mapped to ${mapred.temp.dir} which is undeclared. | Major | conf | Ramya Sunil | Eric Yang
HADOOP-7630 | hadoop-metrics2.properties should have a property *.period set to a default value foe metrics | Major | conf | Arpit Gupta | Eric Yang
HADOOP-7633 | log4j.properties should be added to the hadoop conf on deploy | Major | conf | Arpit Gupta | Eric Yang
HADOOP-7644 | Fix the delegation token tests to use the new style renewers | Blocker | security | Owen O’Malley | Owen O’Malley
MAPREDUCE-3076 | TestSleepJob fails | Blocker | test | Arun C Murthy | Arun C Murthy
HADOOP-7645 | HTTP auth tests requiring Kerberos infrastructure are not disabled on branch-0.20-security | Blocker | security | Aaron T. Myers | Jitendra Nath Pandey
HADOOP-7674 | TestKerberosName fails in 20 branch. | Major | . | Jitendra Nath Pandey | Jitendra Nath Pandey
HDFS-2342 | TestSleepJob and TestHdfsProxy broken after HDFS-2284 | Blocker | build | Kihwal Lee | Tsz Wo Nicholas Sze
HDFS-2325 | Fuse-DFS fails to build on Hadoop 20.203.0 | Blocker | fuse-dfs, libhdfs | Charles Earl | Kihwal Lee
HADOOP-7679 | log4j.properties templates does not define mapred.jobsummary.logger | Major | conf | Ramya Sunil | Ramya Sunil
HDFS-2359 | NPE found in Datanode log while Disk failed during different HDFS operation | Major | datanode | Rajit Saha | Jonathan Eagles
HDFS-2375 | TestFileAppend4 fails in 0.20.205 branch | Blocker | hdfs-client | Suresh Srinivas | Suresh Srinivas
MAPREDUCE-3081 | Change the name format for hadoop core and vaidya jar to be hadoop-{core/vaidya}-{version}.jar in vaidya.sh | Major | contrib/vaidya | vitthal (Suhas) Gogate |
HDFS-2373 | Commands using webhdfs and hftp print unnecessary debug information on the console with security enabled | Major | webhdfs | Arpit Gupta | Arpit Gupta
HDFS-2368 | defaults created for web keytab and principal, these properties should not have defaults | Major | . | Arpit Gupta | Tsz Wo Nicholas Sze
HDFS-2361 | hftp is broken | Critical | namenode | Rajit Saha | Jitendra Nath Pandey
HADOOP-7683 | hdfs-site.xml template has properties that are not used in 20 | Minor | . | Arpit Gupta | Arpit Gupta
HDFS-1260 | 0.20: Block lost when multiple DNs trying to recover it to different genstamps | Critical | . | Todd Lipcon | Todd Lipcon
HDFS-1186 | 0.20: DNs should interrupt writers at start of recovery | Blocker | datanode | Todd Lipcon | Todd Lipcon
HDFS-1218 | 20 append: Blocks recovered on startup should be treated with lower priority during block synchronization | Critical | datanode | Todd Lipcon | Todd Lipcon
HADOOP-7691 | hadoop deb pkg should take a diff group id | Major | . | Giridharan Kesavan | Eric Yang
HADOOP-7603 | Set default hdfs, mapred uid, and hadoop group gid for RPM packages | Major | . | Eric Yang | Eric Yang
HADOOP-7658 | to fix hadoop config template | Major | . | Giridharan Kesavan | Eric Yang
HADOOP-7684 | jobhistory server and secondarynamenode should have init.d script | Major | scripts | Eric Yang | Eric Yang
MAPREDUCE-3112 | Calling hadoop cli inside mapreduce job leads to errors | Major | contrib/streaming | Eric Yang | Eric Yang
HADOOP-7715 | see log4j Error when running mr jobs and certain dfs calls | Major | conf | Arpit Gupta | Eric Yang
HADOOP-7711 | hadoop-env.sh generated from templates has duplicate info | Major | conf | Arpit Gupta | Arpit Gupta
HADOOP-7681 | log4j.properties is missing properties for security audit and hdfs audit should be changed to info | Minor | conf | Arpit Gupta | Arpit Gupta
HADOOP-7708 | config generator does not update the properties file if on exists already | Critical | conf | Arpit Gupta | Eric Yang
HDFS-2358 | NPE when the default filesystem’s uri has no authority | Major | namenode | Rajit Saha | Daryn Sharp
HDFS-2392 | Dist with hftp is failing again | Critical | namenode | Rajit Saha | Daryn Sharp
HDFS-2408 | DFSClient#getNumCurrentReplicas is package private in 205 but public in branch-0.20-append | Blocker | hdfs-client | stack | stack
HADOOP-7721 | dfs.web.authentication.kerberos.principal expects the full hostname and does not replace _HOST with the hostname | Major | . | Arpit Gupta | Jitendra Nath Pandey
HDFS-2405 | hadoop dfs command with webhdfs fails on secure hadoop | Critical | webhdfs | Arpit Gupta | Jitendra Nath Pandey
HADOOP-7724 | hadoop-setup-conf.sh should put proxy user info into the core-site.xml | Major | . | Giridharan Kesavan | Arpit Gupta
MAPREDUCE-2764 | Fix renewal of dfs delegation tokens | Major | . | Daryn Sharp | Owen O’Malley
HADOOP-7602 | wordcount, sort etc on har files fails with NPE | Major | . | John George | John George
HADOOP-7649 | TestMapredGroupMappingServiceRefresh and TestRefreshUserMappings fail after HADOOP-7625 | Blocker | security, test | Kihwal Lee | Jitendra Nath Pandey
HDFS-2411 | with webhdfs enabled in secure mode the auth to local mappings are not being respected. | Major | webhdfs | Arpit Gupta | Jitendra Nath Pandey
HDFS-1197 | Blocks are considered “complete” prematurely after commitBlockSynchronization or DN restart | Major | datanode, hdfs-client, namenode | Todd Lipcon | Todd Lipcon
HADOOP-7615 | Binary layout does not put share/hadoop/contrib/*.jar into the class path | Major | scripts | Eric Yang | Eric Yang
HDFS-2300 | TestFileAppend4 and TestMultiThreadedSync fail on 20.append and 20-security. | Major | . | Jitendra Nath Pandey | Jitendra Nath Pandey

### TESTS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-1242 | 0.20 append: Add test for appendFile() race solved in HDFS-142 | Major | . | Todd Lipcon | Todd Lipcon
HDFS-1252 | TestDFSConcurrentFileOperations broken in 0.20-appendj | Major | test | Todd Lipcon | Todd Lipcon

### SUB-TASKS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-561 | Fix write pipeline READ_TIMEOUT | Major | datanode, hdfs-client | Kan Zhang | Kan Zhang
HDFS-1057 | Concurrent readers hit ChecksumExceptions if following a writer to very end of file | Blocker | datanode | Todd Lipcon | sam rash
HDFS-2284 | Write Http access to HDFS | Major | . | Sanjay Radia | Tsz Wo Nicholas Sze
HDFS-2317 | Read access to HDFS using HTTP REST | Major | . | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
HDFS-2338 | Configuration option to enable/disable webhdfs. | Major | webhdfs | Jitendra Nath Pandey | Jitendra Nath Pandey
HDFS-2318 | Provide authentication to webhdfs using SPNEGO | Major | webhdfs | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
HDFS-2340 | Support getFileBlockLocations and getDelegationToken in webhdfs | Major | webhdfs | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
MAPREDUCE-2928 | MR-2413 improvements | Major | tasktracker | Eli Collins | Eli Collins
HDFS-2356 | webhdfs: support case insensitive query parameter names | Major | webhdfs | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
HDFS-2366 | webhdfs throws a npe when ugi is null from getDelegationToken | Major | webhdfs | Arpit Gupta | Tsz Wo Nicholas Sze
HDFS-2348 | Support getContentSummary and getFileChecksum in webhdfs | Major | webhdfs | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
HDFS-2395 | webhdfs api’s should return a root element in the json response | Critical | webhdfs | Arpit Gupta | Tsz Wo Nicholas Sze
HDFS-2403 | The renewer in NamenodeWebHdfsMethods.generateDelegationToken(..) is not used | Major | . | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
HDFS-2404 | webhdfs liststatus json response is not correct | Major | webhdfs | Arpit Gupta | Suresh Srinivas
HDFS-2385 | Support delegation token renewal in webhdfs | Major | webhdfs | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
MAPREDUCE-2780 | Standardize the value of token service | Major | . | Daryn Sharp | Daryn Sharp

### OTHER:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-1795 | Port 0.20-append changes onto 0.20-security-203 | Major | . | Andrew Purtell |