##### 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 2.1.0-beta Release Notes

These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.

- MAPREDUCE-3787 | Major | [Gridmix] Improve STRESS mode

JobMonitor can now deploy multiple threads for faster job-status polling. Use ‘gridmix.job-monitor.thread-count’ to set the number of threads. Stress mode now relies on the updates from the job monitor instead of polling for job status. Failures in job submission now get reported to the statistics module and ultimately reported to the user via summary.

- MAPREDUCE-2722 | Major | Gridmix simulated job’s map’s hdfsBytesRead counter is wrong when compressed input is used

Makes Gridmix use the uncompressed input data size while simulating map tasks in the case where compressed input data was used in original job.

- MAPREDUCE-3829 | Major | [Gridmix] Gridmix should give better error message when input-data directory already exists and -generate option is given

Makes Gridmix emit out correct error message when the input data directory already exists and -generate option is used. Makes Gridmix exit with proper exit codes when Gridmix fails in args-processing, startup/setup.

- MAPREDUCE-3953 | Major | Gridmix throws NPE and does not simulate a job if the trace contains null taskStatus for a task

Fixes NPE and makes Gridmix simulate succeeded-jobs-with-failed-tasks. All tasks of such simulated jobs(including the failed ones of original job) will succeed.

- MAPREDUCE-3757 | Major | Rumen Folder is not adjusting the shuffleFinished and sortFinished times of reduce task attempts

Fixed the sortFinishTime and shuffleFinishTime adjustments in Rumen Folder.

- MAPREDUCE-4083 | Major | GridMix emulated job tasks.resource-usage emulator for CPU usage throws NPE when Trace contains cumulativeCpuUsage value of 0 at attempt level

Fixes NPE in cpu emulation in Gridmix

- MAPREDUCE-4149 | Major | Rumen fails to parse certain counter strings

Fixes Rumen to parse counter strings containing the special characters “{” and “}”.

- MAPREDUCE-4100 | Minor | Sometimes gridmix emulates data larger much larger then acutal counter for map only jobs

Bug fixed in compression emulation feature for map only jobs.

- MAPREDUCE-4356 | Major | Provide access to ParsedTask.obtainTaskAttempts()

Made the method ParsedTask.obtainTaskAttempts() public.

- HADOOP-8886 | Major | Remove KFS support

Kosmos FS (KFS) is no longer maintained and Hadoop support has been removed. KFS has been replaced by QFS (HADOOP-8885).

- HDFS-4053 | Major | Increase the default block size

The default blocks size prior to this change was 64MB. This jira changes the default block size to 128MB. To go back to previous behavior, please configure the in hdfs-site.xml, the configuration parameter “dfs.blocksize” to 67108864.

- HADOOP-9163 | Major | The rpc msg in ProtobufRpcEngine.proto should be moved out to avoid an extra copy

WARNING: No release note provided for this change.

- HDFS-4519 | Major | Support override of jsvc binary and log file locations when launching secure datanode.

With this improvement the following options are available in release 1.2.0 and later on 1.x release stream: 1. jsvc location can be overridden by setting environment variable JSVC_HOME. Defaults to jsvc binary packaged within the Hadoop distro. 2. jsvc log output is directed to the file defined by JSVC_OUTFILE. Defaults to $HADOOP_LOG_DIR/jsvc.out. 3. jsvc error output is directed to the file defined by JSVC_ERRFILE file. Defaults to $HADOOP_LOG_DIR/jsvc.err.

With this improvement the following options are available in release 2.0.4 and later on 2.x release stream: 1. jsvc log output is directed to the file defined by JSVC_OUTFILE. Defaults to $HADOOP_LOG_DIR/jsvc.out. 2. jsvc error output is directed to the file defined by JSVC_ERRFILE file. Defaults to $HADOOP_LOG_DIR/jsvc.err.

For overriding jsvc location on 2.x releases, here is the release notes from HDFS-2303: To run secure Datanodes users must install jsvc for their platform and set JSVC_HOME to point to the location of jsvc in their environment.

- HADOOP-9151 | Major | Include RPC error info in RpcResponseHeader instead of sending it separately

WARNING: No release note provided for this change.

- YARN-396 | Major | Rationalize AllocateResponse in RM scheduler API

WARNING: No release note provided for this change.

- HADOOP-9380 | Major | Add totalLength to rpc response

WARNING: No release note provided for this change.

- HADOOP-9228 | Minor | FileSystemContractTestBase never verifies that files are files

fixed in HADOOP-9258

- HADOOP-9227 | Trivial | FileSystemContractBaseTest doesn’t test filesystem’s mkdir/isDirectory() logic rigorously enough

fixed in HADOOP-9258

- YARN-439 | Major | Flatten NodeHeartbeatResponse

WARNING: No release note provided for this change.

- YARN-440 | Major | Flatten RegisterNodeManagerResponse

WARNING: No release note provided for this change.

- HADOOP-9194 | Major | RPC Support for QoS

Part of the RPC version 9 change. A service class byte is added after the version byte.

- YARN-536 | Major | Remove ContainerStatus, ContainerState from Container api interface as they will not be called by the container object

WARNING: No release note provided for this change.

- HDFS-1804 | Minor | Add a new block-volume device choosing policy that looks at free space

There is now a new option to have the DN take into account available disk space on each volume when choosing where to place a replica when performing an HDFS write. This can be enabled by setting the config “dfs.datanode.fsdataset.volume.choosing.policy” to the value “org.apache.hadoop.hdfs.server.datanode.fsdataset.AvailableSpaceVolumeChoosingPolicy”.

- YARN-561 | Major | Nodemanager should set some key information into the environment of every container that it launches.

WARNING: No release note provided for this change.

- MAPREDUCE-4737 | Major | ** Hadoop does not close output file / does not call Mapper.cleanup if exception in map**

Ensure that mapreduce APIs are semantically consistent with mapred API w.r.t Mapper.cleanup and Reducer.cleanup; in the sense that cleanup is now called even if there is an error. The old mapred API already ensures that Mapper.close and Reducer.close are invoked during error handling. Note that it is an incompatible change, however end-users can override Mapper.run and Reducer.run to get the old (inconsistent) behaviour.

- HDFS-4305 | Minor | Add a configurable limit on number of blocks per file, and min block size

This change introduces a maximum number of blocks per file, by default one million, and a minimum block size, by default 1MB. These can optionally be changed via the configuration settings “dfs.namenode.fs-limits.max-blocks-per-file” and “dfs.namenode.fs-limits.min-block-size”, respectively.

- YARN-579 | Major | Make ApplicationToken part of Container’s token list to help RM-restart

WARNING: No release note provided for this change.

- HDFS-4659 | Major | Support setting execution bit for regular files

WARNING: No release note provided for this change.

- HDFS-4434 | Major | Provide a mapping from INodeId to INode

This change adds support for referencing files and directories based on fileID/inodeID using a path /.reserved/.inodes/<inodeid>. With this change creating a file or directory /.reserved is not longer allowed. Before upgrading to a release with this change, files /.reserved needs to be renamed to another name.

- HADOOP-9425 | Major | Add error codes to rpc-response

WARNING: No release note provided for this change.

- YARN-629 | Major | Make YarnRemoteException not be rooted at IOException

WARNING: No release note provided for this change.

- YARN-633 | Major | Change RMAdminProtocol api to throw IOException and YarnRemoteException

WARNING: No release note provided for this change.

- YARN-632 | Major | Change ContainerManager api to throw IOException and YarnRemoteException

WARNING: No release note provided for this change.

- YARN-631 | Major | Change ClientRMProtocol api to throw IOException and YarnRemoteException

WARNING: No release note provided for this change.

- YARN-630 | Major | Change AMRMProtocol api to throw IOException and YarnRemoteException

WARNING: No release note provided for this change.

- MAPREDUCE-4067 | Critical | Replace YarnRemoteException with IOException in MRv2 APIs

WARNING: No release note provided for this change.

- YARN-615 | Major | ContainerLaunchContext.containerTokens should simply be called tokens

WARNING: No release note provided for this change.

- MAPREDUCE-5234 | Major | Signature changes for getTaskId of TaskReport in mapred

WARNING: No release note provided for this change.

- MAPREDUCE-5156 | Blocker | Hadoop-examples-1.x.x.jar cannot run on Yarn

WARNING: No release note provided for this change.

- MAPREDUCE-5233 | Major | Functions are changed or removed from Job in jobcontrol

WARNING: No release note provided for this change.

- HADOOP-8562 | Major | Enhancements to support Hadoop on Windows Server and Windows Azure environments

This umbrella jira makes enhancements to support Hadoop natively on Windows Server and Windows Azure environments.

- YARN-571 | Major | User should not be part of ContainerLaunchContext

WARNING: No release note provided for this change.

- MAPREDUCE-5237 | Major | ClusterStatus incompatiblity issues with MR1

WARNING: No release note provided for this change.

- YARN-716 | Major | Make ApplicationID immutable

WARNING: No release note provided for this change.

- YARN-684 | Major | ContainerManager.startContainer needs to only have ContainerTokenIdentifier instead of the whole Container

WARNING: No release note provided for this change.

- MAPREDUCE-5176 | Major | Preemptable annotations (to support preemption in MR)

WARNING: No release note provided for this change.

- YARN-735 | Major | Make ApplicationAttemptID, ContainerID, NodeID immutable

WARNING: No release note provided for this change.

- YARN-749 | Major | Rename ResourceRequest (get,set)HostName to (get,set)ResourceName

WARNING: No release note provided for this change.

- YARN-720 | Major | container-log4j.properties should not refer to mapreduce properties

WARNING: No release note provided for this change.

- HADOOP-8470 | Major | Implementation of 4-layer subclass of NetworkTopology (NetworkTopologyWithNodeGroup)

This patch should be checked in together (or after) with JIRA Hadoop-8469: https://issues.apache.org/jira/browse/HADOOP-8469

- MAPREDUCE-5300 | Major | Two function signature changes in filecache.DistributedCache

WARNING: No release note provided for this change.

- YARN-748 | Major | Move BuilderUtils from yarn-common to yarn-server-common

WARNING: No release note provided for this change.

- YARN-635 | Major | Rename YarnRemoteException to YarnException

WARNING: No release note provided for this change.

- YARN-755 | Major | Rename AllocateResponse.reboot to AllocateResponse.resync

WARNING: No release note provided for this change.

- YARN-756 | Major | Move PreemptionContainer/PremptionContract/PreemptionMessage/StrictPreemptionContract/PreemptionResourceRequest to api.records

WARNING: No release note provided for this change.

- YARN-753 | Major | Add individual factory method for api protocol records

WARNING: No release note provided for this change.

- YARN-724 | Major | Move ProtoBase from api.records to api.records.impl.pb

WARNING: No release note provided for this change.

- HDFS-4832 | Critical | Namenode doesn’t change the number of missing blocks in safemode when DNs rejoin or leave

This change makes name node keep its internal replication queues and data node state updated in manual safe mode. This allows metrics and UI to present up-to-date information while in safe mode. The behavior during start-up safe mode is unchanged.

- YARN-777 | Major | Remove unreferenced objects from proto

WARNING: No release note provided for this change.

- YARN-642 | Major | Fix up /nodes REST API to have 1 param and be consistent with the Java API

WARNING: No release note provided for this change.

- HADOOP-9630 | Major | Remove IpcSerializationType

WARNING: No release note provided for this change.

- MAPREDUCE-5304 | Blocker | mapreduce.Job killTask/failTask/getTaskCompletionEvents methods have incompatible signature changes

WARNING: No release note provided for this change.

- YARN-530 | Major | Define Service model strictly, implement AbstractService for robust subclassing, migrate yarn-common services

WARNING: No release note provided for this change.

- YARN-746 | Major | rename Service.register() and Service.unregister() to registerServiceListener() & unregisterServiceListener() respectively

WARNING: No release note provided for this change.

- YARN-792 | Major | Move NodeHealthStatus from yarn.api.record to yarn.server.api.record

WARNING: No release note provided for this change.

- YARN-806 | Major | Move ContainerExitStatus from yarn.api to yarn.api.records

WARNING: No release note provided for this change.

- MAPREDUCE-4942 | Major | mapreduce.Job has a bunch of methods that throw InterruptedException so its incompatible with MR1

WARNING: No release note provided for this change.

- HDFS-4866 | Blocker | Protocol buffer support cannot compile under C

The Protocol Buffers definition of the inter-namenode protocol required a change for compatibility with compiled C clients. This is a backwards-incompatible change. A namenode prior to this change will not be able to communicate with a namenode after this change.

- YARN-821 | Major | Rename FinishApplicationMasterRequest.setFinishApplicationStatus to setFinalApplicationStatus to be consistent with getter

WARNING: No release note provided for this change.

- YARN-787 | Blocker | Remove resource min from Yarn client API

WARNING: No release note provided for this change.

- MAPREDUCE-5184 | Major | Document MR Binary Compatibility vis-a-vis hadoop-1 and hadoop-2

Document MR Binary Compatibility vis-a-vis hadoop-1 and hadoop-2 for end-users.

- YARN-829 | Major | Rename RMTokenSelector to be RMDelegationTokenSelector

WARNING: No release note provided for this change.

- YARN-828 | Major | Remove YarnVersionAnnotation

WARNING: No release note provided for this change.

- YARN-823 | Major | Move RMAdmin from yarn.client to yarn.client.cli and rename as RMAdminCLI

WARNING: No release note provided for this change.

- YARN-387 | Blocker | Fix inconsistent protocol naming

WARNING: No release note provided for this change.

- YARN-831 | Blocker | Remove resource min from GetNewApplicationResponse

WARNING: No release note provided for this change.

- YARN-824 | Major | Add static factory to yarn client lib interface and change it to abstract class

WARNING: No release note provided for this change.

- YARN-826 | Major | Move Clock/SystemClock to util package

WARNING: No release note provided for this change.

- HADOOP-9649 | Blocker | Promote YARN service life-cycle libraries into Hadoop Common

WARNING: No release note provided for this change.

- YARN-837 | Major | ClusterInfo.java doesn’t seem to belong to org.apache.hadoop.yarn

WARNING: No release note provided for this change.

- YARN-822 | Major | Rename ApplicationToken to AMRMToken

WARNING: No release note provided for this change.

- YARN-610 | Blocker | ClientToken (ClientToAMToken) should not be set in the environment

WARNING: No release note provided for this change.

- YARN-834 | Blocker | Review/fix annotations for yarn-client module and clearly differentiate *Async apis

WARNING: No release note provided for this change.

- YARN-840 | Major | Move ProtoUtils to yarn.api.records.pb.impl

WARNING: No release note provided for this change.

- YARN-841 | Major | Annotate and document AuxService APIs

WARNING: No release note provided for this change.

- YARN-694 | Major | Start using NMTokens to authenticate all communication with NM

WARNING: No release note provided for this change.

- YARN-553 | Minor | Have YarnClient generate a directly usable ApplicationSubmissionContext

WARNING: No release note provided for this change.

- YARN-851 | Major | Share NMTokens using NMTokenCache (api-based) instead of memory based approach which is used currently.

WARNING: No release note provided for this change.

- HADOOP-9421 | Blocker | Convert SASL to use ProtoBuf and provide negotiation capabilities

Raw SASL protocol now uses protobufs wrapped with RPC headers. The negotiation sequence incorporates the state of the exchange. The server now has the ability to advertise its supported auth types.

- YARN-869 | Blocker | ResourceManagerAdministrationProtocol should neither be public(yet) nor in yarn.api

WARNING: No release note provided for this change.

- YARN-791 | Blocker | Ensure that RM RPC APIs that return nodes are consistent with /nodes REST API

WARNING: No release note provided for this change.

- HADOOP-9683 | Blocker | Wrap IpcConnectionContext in RPC headers

Connection context is now sent as a rpc header wrapped protobuf.

- YARN-701 | Blocker | ApplicationTokens should be used irrespective of kerberos

WARNING: No release note provided for this change.

- HDFS-4996 | Minor | ClientProtocol#metaSave can be made idempotent by overwriting the output file instead of appending to it

The dfsadmin -metasave command has been changed to overwrite the output file. Previously, this command would append to the output file if it already existed.

- YARN-918 | Blocker | ApplicationMasterProtocol doesn’t need ApplicationAttemptId in the payload after YARN-701

WARNING: No release note provided for this change.

- YARN-926 | Blocker | ContainerManagerProtcol APIs should take in requests for multiple containers

WARNING: No release note provided for this change.

- HADOOP-9698 | Blocker | RPCv9 client must honor server’s SASL negotiate response

The RPC client now waits for the Server’s SASL negotiate response before instantiating its SASL client.

- HADOOP-9832 | Blocker | Add RPC header to client ping

Client ping will be sent as a RPC header with a reserved callId instead of as a sentinel RPC packet length.

- MAPREDUCE-5399 | Blocker | Unnecessary Configuration instantiation in IFileInputStream slows down merge

Fixes blank Configuration object creation overhead by reusing the Job configuration in InMemoryReader.

- HADOOP-9820 | Blocker | RPCv9 wire protocol is insufficient to support multiplexing

WARNING: No release note provided for this change.

- HDFS-5083 | Blocker | Update the HDFS compatibility version range

WARNING: No release note provided for this change.

- YARN-1056 | Trivial | Fix configs yarn.resourcemanager.resourcemanager.connect.{max.wait.secs|retry_interval.secs}

WARNING: No release note provided for this change.

- HDFS-2802 | Major | Support for RW/RO snapshots in HDFS

WARNING: No release note provided for this change.