Overview of Version 1

Master - HMaster is the implementation of the Master Server. The Master server - is responsible for monitoring all RegionServer instances in the cluster, and is - the interface for all metadata changes. In a distributed cluster, the Master typically runs on the - J Mohamed Zahoor goes into some more detail on the Master Architecture in this blog posting, HBase HMaster Architecture - . - - + HMaster is the implementation of the Master Server. The Master server is + responsible for monitoring all RegionServer instances in the cluster, and is the interface + for all metadata changes. In a distributed cluster, the Master typically runs on the . J Mohamed Zahoor goes into some more detail on the Master + Architecture in this blog posting, HBase HMaster + Architecture .

Startup Behavior If run in a multi-Master environment, all Masters compete to run the cluster. If the active Master loses its lease in ZooKeeper (or the Master shuts down), then then the remaining Masters jostle to @@ -2469,17 +2456,16 @@ rs.close(); physical RAM, and is likely to be less than the total available RAM due to other memory requirements and system constraints. - You can see how much memory -- onheap and offheap/direct -- a RegionServer is configured to use - and how much it is using at any one time by looking at the - Server Metrics: Memory tab in the UI. - It can also be gotten via JMX. In particular the direct - memory currently used by the server can be found on the - java.nio.type=BufferPool,name=direct - bean. - Terracotta has a good write up on using offheap memory in java. - It is for their product BigMemory but alot of the issues noted apply - in general to any attempt at going offheap. Check it out. - + You can see how much memory -- onheap and offheap/direct -- a RegionServer is + configured to use and how much it is using at any one time by looking at the + Server Metrics: Memory tab in the UI. It can also be gotten + via JMX. In particular the direct memory currently used by the server can be found + on the java.nio.type=BufferPool,name=direct bean. Terracotta has + a good write up on using offheap memory in java. It is for their product + BigMemory but alot of the issues noted apply in general to any attempt at going + offheap. Check it out. hbase.bucketcache.percentage.in.combinedcache This is a pre-HBase 1.0 configuration removed because it @@ -2613,12 +2599,10 @@ rs.close(); If the hbase.hlog.split.skip.errors optionset to false, the default, the exception will be propagated and the - split will be logged as failed. - See HBASE-2958 When hbase.hlog.split.skip.errors is set to false, we fail the split but thats it. We need to do more than just fail split if this flag is set. -

How EOFExceptions are treated when splitting a crashed RegionServers' @@ -2628,11 +2612,9 @@ rs.close(); <varname>hbase.hlog.split.skip.errors</varname> is set to <literal>false</literal>. An EOFException while reading the last log in the set of files to split is likely, because the RegionServer is likely to be in the process of - writing a record at the time of a crash. <footnote> - <para>For background, see <link + writing a record at the time of a crash. For background, see <link xlink:href="https://issues.apache.org/jira/browse/HBASE-2643">HBASE-2643 Figure how to deal with eof splitting logs</link></para> - </footnote></para> </section> </section> @@ -3042,9 +3024,9 @@ ctime = Sat Jun 23 11:13:40 PDT 2012 </listitem> <listitem><para>Third replica is written on the same rack as the second, but on a different node chosen randomly</para> </listitem> - <listitem><para>Subsequent replicas are written on random nodes on the cluster -<footnote><para>See <emphasis>Replica Placement: The First Baby Steps</emphasis> on this page: <link xlink:href="http://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-hdfs/HdfsDesign.html">HDFS Architecture</link></para></footnote> - </para></listitem> + <listitem><para>Subsequent replicas are written on random nodes on the cluster. See <emphasis>Replica Placement: The First Baby Steps</emphasis> on this page: <link + xlink:href="http://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-hdfs/HdfsDesign.html" + >HDFS Architecture</link></para></listitem> </orderedlist> <para> Thus, HBase eventually achieves locality for a region after a flush or a compaction. @@ -5166,8 +5148,7 @@ This option should not normally be used, and it is not in <code>-fixAll</code>. <imageobject> <imagedata fileref="data_block_no_encoding.png" width="800"/> </imageobject> - <textobject><para></para> - </textobject> + <caption><para>A ColumnFamily with no encoding></para></caption> </mediaobject> </figure> <para>Here is the same data with prefix data encoding.</para> @@ -5177,8 +5158,7 @@ This option should not normally be used, and it is not in <code>-fixAll</code>. <imageobject> <imagedata fileref="data_block_prefix_encoding.png" width="800"/> </imageobject> - <textobject><para></para> - </textobject> + <caption><para>A ColumnFamily with prefix encoding</para></caption> </mediaobject> </figure> </listitem> @@ -5202,8 +5182,7 @@ This option should not normally be used, and it is not in <code>-fixAll</code>. <imageobject> <imagedata fileref="data_block_diff_encoding.png" width="800"/> </imageobject> - <textobject><para></para> - </textobject> + <caption><para>A ColumnFamily with diff encoding</para></caption> </mediaobject> </figure> </listitem> http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/community.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/community.xml b/src/main/docbkx/community.xml index 9bdaa39..813f356 100644 --- a/src/main/docbkx/community.xml +++ b/src/main/docbkx/community.xml @@ -40,12 +40,9 @@ committer will add it for you. Thereafter you can file issues against your feature branch in Apache HBase JIRA. Your code you keep elsewhere -- it should be public so it can be observed -- and you can update dev mailing list on progress. When the feature is ready for commit, 3 - +1s from committers will get your feature merged<footnote> - <para>See <link + +1s from committers will get your feature merged. See <link xlink:href="http://search-hadoop.com/m/asM982C5FkS1">HBase, mail # dev - Thoughts about large feature dev branches</link></para> - </footnote> - </para> </section> <section xml:id="patchplusonepolicy"> http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/configuration.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/configuration.xml b/src/main/docbkx/configuration.xml index 898aa85..0af2b3c 100644 --- a/src/main/docbkx/configuration.xml +++ b/src/main/docbkx/configuration.xml @@ -212,12 +212,10 @@ <term>DNS</term> <listitem> <para>HBase uses the local hostname to self-report its IP address. Both forward and - reverse DNS resolving must work in versions of HBase previous to 0.92.0.<footnote> - <para>The <link + reverse DNS resolving must work in versions of HBase previous to 0.92.0. The <link xlink:href="https://github.com/sujee/hadoop-dns-checker">hadoop-dns-checker</link> tool can be used to verify DNS is working correctly on the cluster. The project README file provides detailed instructions on usage. </para> - </footnote></para> <para>If your server has multiple network interfaces, HBase defaults to using the interface that the primary hostname resolves to. To override this behavior, set the @@ -306,11 +304,10 @@ running the HBase process is an operating system configuration, rather than an HBase configuration. It is also important to be sure that the settings are changed for the user that actually runs HBase. To see which user started HBase, and that user's ulimit - configuration, look at the first line of the HBase log for that instance.<footnote> - <para>A useful read setting config on you hadoop cluster is Aaron Kimballs' <link - xlink:href="http://www.cloudera.com/blog/2009/03/configuration-parameters-what-can-you-just-ignore/">Configuration - Parameters: What can you just ignore?</link></para> - </footnote></para> + configuration, look at the first line of the HBase log for that instance. A useful read + setting config on you hadoop cluster is Aaron Kimballs' <link + xlink:href="http://www.cloudera.com/blog/2009/03/configuration-parameters-what-can-you-just-ignore/" + >Configuration Parameters: What can you just ignore?</link></para> <formalpara xml:id="ulimit_ubuntu"> <title><command>ulimit</command> Settings on Ubuntu To configure ulimit settings on Ubuntu, edit @@ -414,12 +411,8 @@ hadoop - nproc 32000 HBase-0.92.x HBase-0.94.x HBase-0.96.x - HBase-0.98.x - Support for Hadoop 1.x is deprecated. - - HBase-1.0.x - Hadoop 1.x is NOT supported - + HBase-0.98.x (Support for Hadoop 1.x is deprecated.) + HBase-1.0.x (Hadoop 1.x is NOT supported) @@ -440,11 +433,9 @@ hadoop - nproc 32000 X - Hadoop-1.0.0-1.0.2 - HBase requires hadoop 1.0.3 at a minimum; there is an issue where we cannot - find KerberosUtil compiling against earlier versions of Hadoop. - - + Hadoop-1.0.0-1.0.2 (HBase requires hadoop 1.0.3 at a minimum; there is an + issue where we cannot find KerberosUtil compiling against earlier versions of + Hadoop.) X X X @@ -494,10 +485,9 @@ hadoop - nproc 32000 Hadoop-2.2.0 X - NT - To get 0.94.x to run on hadoop 2.2.0, you need to change the hadoop 2 and - protobuf versions in the pom.xml: Here is a diff with - pom.xml changes: + NT - To get 0.94.x to run on hadoop 2.2.0, you need to change the hadoop + 2 and protobuf versions in the pom.xml: Here is a diff with + pom.xml changes: Building against the hadoop 2 profile by running something like the following command: - $ mvn clean install assembly:single -Dhadoop.profile=2.0 -DskipTests - + $ mvn clean install assembly:single -Dhadoop.profile=2.0 -DskipTests S S NT @@ -601,11 +590,9 @@ Index: pom.xml As of Apache HBase 0.96.x, Apache Hadoop 1.0.x at least is required. Hadoop 2 is strongly encouraged (faster but also has fixes that help MTTR). We will no longer run properly on older Hadoops such as 0.20.205 or branch-0.20-append. Do not move to Apache - HBase 0.96.x if you cannot upgrade your Hadoop. - See HBase, mail # dev - DISCUSS: Have hbase require at least hadoop 1.0.0 in hbase 0.96.0? -

sync implementation. DO NOT use Hadoop 0.20.2, Hadoop 0.20.203.0, and Hadoop 0.20.204.0 which DO NOT have this attribute. Currently only Hadoop versions 0.20.205.x or any release in excess of this version -- this includes hadoop-1.0.0 -- have - a working, durable sync - The Cloudera blog post An - update on Apache Hadoop 1.0 by Charles Zedlweski has a nice exposition on how - all the Hadoop versions relate. Its worth checking out if you are having trouble - making sense of the Hadoop version morass. - . Sync has to be explicitly enabled by setting + a working, durable sync. The Cloudera blog post An + update on Apache Hadoop 1.0 by Charles Zedlweski has a nice exposition on how all + the Hadoop versions relate. Its worth checking out if you are having trouble making sense + of the Hadoop version morass. + Sync has to be explicitly enabled by setting dfs.support.append equal to true on both the client side -- in hbase-site.xml -- and on the serverside in hdfs-site.xml (The sync facility HBase needs is a subset of the @@ -713,9 +699,7 @@ Index: pom.xml Distributed mode can be subdivided into distributed but all daemons run on a single node -- a.k.a pseudo-distributed-- and fully-distributed where the daemons are spread across all nodes in - the cluster - The pseudo-distributed vs fully-distributed nomenclature comes from Hadoop. - . + the cluster. The pseudo-distributed vs fully-distributed nomenclature comes from Hadoop. Pseudo-distributed mode can run against the local filesystem or it can run against an instance of the Hadoop Distributed File System (HDFS). http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/cp.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/cp.xml b/src/main/docbkx/cp.xml index 4ddc8c1..8624309 100644 --- a/src/main/docbkx/cp.xml +++ b/src/main/docbkx/cp.xml @@ -29,16 +29,14 @@ */ --> Apache HBase Coprocessors - HBase coprocessors are modeled after the coprocessors which are part of Google's BigTable - , pages - 66-67. - . Coprocessors function in a similar way to Linux kernel modules. They provide a way - to run server-level code against locally-stored data. The functionality they provide is very + HBase coprocessors are modeled after the coprocessors which are part of Google's BigTable + (, pages + 66-67.). Coprocessors function in a similar way to Linux kernel modules. They provide a way to + run server-level code against locally-stored data. The functionality they provide is very powerful, but also carries great risk and can have adverse effects on the system, at the level of the operating system. The information in this chapter is primarily sourced and heavily reused from Mingjie Lai's blog post at . + xlink:href="https://blogs.apache.org/hbase/entry/coprocessor_introduction"/>. Coprocessors are not designed to be used by end users of HBase, but by HBase developers who need to add specialized functionality to HBase. One example of the use of coprocessors is @@ -418,10 +416,10 @@ coprocessors=[AggregateImplementation] - + The Coprocessor Metrics UI shows statistics about time spent executing a given coprocessor, including min, max, average, and 90th, 95th, and 99th percentile. - +

http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/ops_mgt.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/ops_mgt.xml b/src/main/docbkx/ops_mgt.xml index 7328f67..21045bd 100644 --- a/src/main/docbkx/ops_mgt.xml +++ b/src/main/docbkx/ops_mgt.xml @@ -757,11 +757,9 @@ false Without this facility, decommissioning mulitple nodes may be non-optimal because regions that are being drained from one region server may be moved to other regionservers that are also draining. Marking RegionServers to be in the draining state prevents this - from happening - See this blog - post for more details. - . + from happening. See this blog + post for more details.

- + Shows the cache implementation - +

@@ -1217,9 +1215,9 @@ $ for i in `cat conf/regionservers|sort`; do ./bin/graceful_stop.sh --restart -- - + Shows all cache configuration options. - +

@@ -1228,9 +1226,9 @@ $ for i in `cat conf/regionservers|sort`; do ./bin/graceful_stop.sh --restart -- - + Shows statistics about the performance of the cache. - +

@@ -1242,9 +1240,9 @@ $ for i in `cat conf/regionservers|sort`; do ./bin/graceful_stop.sh --restart -- - + Shows information about the L1 and L2 caches. - + This is not an exhaustive list of all the screens and reports available. Have a look in @@ -1305,10 +1303,10 @@ $ for i in `cat conf/regionservers|sort`; do ./bin/graceful_stop.sh --restart -- - + Illustration of the replication architecture in HBase, as described in the prior text. - + http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/performance.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/performance.xml b/src/main/docbkx/performance.xml index 1940663..e7c0fc7 100644 --- a/src/main/docbkx/performance.xml +++ b/src/main/docbkx/performance.xml @@ -146,8 +146,7 @@ xml:id="gcpause"> Long GC pauses - In his presentation, In his presentation, Avoiding Full GCs with MemStore-Local Allocation Buffers, Todd Lipcon describes two cases of stop-the-world garbage collections common in HBase, especially during loading; CMS failure @@ -158,16 +157,16 @@ Todd added an experimental facility, MSLAB, that must be explicitly enabled in Apache HBase 0.90.x (Its defaulted to be on in Apache 0.92.x HBase). See hbase.hregion.memstore.mslab.enabled to true in your - Configuration. See the cited slides for background and detail - The latest jvms do better regards fragmentation so make sure you are running a - recent release. Read down in the message, Identifying - concurrent mode failures caused by fragmentation. - . Be aware that when enabled, each MemStore instance will occupy at least an - MSLAB instance of memory. If you have thousands of regions or lots of regions each with - many column families, this allocation of MSLAB may be responsible for a good portion of - your heap allocation and in an extreme case cause you to OOME. Disable MSLAB in this case, - or lower the amount of memory it uses or float less regions per server. + Configuration. See the cited slides for background and detail. + The latest jvms do better regards fragmentation so make sure you are running a recent + release. Read down in the message, Identifying + concurrent mode failures caused by fragmentation. Be aware that when enabled, + each MemStore instance will occupy at least an MSLAB instance of memory. If you have + thousands of regions or lots of regions each with many column families, this allocation of + MSLAB may be responsible for a good portion of your heap allocation and in an extreme case + cause you to OOME. Disable MSLAB in this case, or lower the amount of memory it uses or + float less regions per server. If you have a write-heavy workload, check out HBASE-8163 MemStoreChunkPool: An improvement for JAVA GC when using MSLAB. It describes @@ -916,24 +915,20 @@ htable.close(); latencies. Bloom filters were developed - over in HBase-1200 Add - bloomfilters. - For description of the development process -- why static blooms rather than dynamic + over in HBase-1200 Add + bloomfilters. For description of the development process -- why static blooms rather than dynamic -- and for an overview of the unique properties that pertain to blooms in HBase, as well as possible future directions, see the Development Process section of the document BloomFilters in HBase attached to HBase-1200. - - The bloom filters described here are actually version two of blooms in HBase. In + xlink:href="https://issues.apache.org/jira/browse/HBASE-1200">HBase-1200. The bloom filters described here are actually version two of blooms in HBase. In versions up to 0.19.x, HBase had a dynamic bloom option based on work done by the European Commission One-Lab Project 034819. The core of the HBase bloom work was later pulled up into Hadoop to implement org.apache.hadoop.io.BloomMapFile. Version 1 of HBase blooms never worked that well. Version 2 is a rewrite from scratch though again it starts with the one-lab work. - + See also . @@ -1047,11 +1042,9 @@ htable.close(); possible for the DFSClient to take a "short circuit" and read directly from the disk instead of going through the DataNode when the data is local. What this means for HBase is that the RegionServers can read directly off their machine's disks instead of having to open a socket - to talk to the DataNode, the former being generally much faster - See JD's Performance - Talk - . Also see . Also see HBase, mail # dev - read short circuit thread for more discussion around short circuit reads. To enable "short circuit" reads, it will depend on your version of Hadoop. The original @@ -1081,19 +1074,17 @@ htable.close(); ]]> Be careful about permissions for the directory that hosts the shared domain socket; - dfsclient will complain if open to other than the hbase user. - If you are running on an old Hadoop, one that is without HDFS-347 but that - has HDFS-2246, you - must set two configurations. First, the hdfs-site.xml needs to be amended. Set the - property dfs.block.local-path-access.user to be the - only user that can use the shortcut. This has to be the user that - started HBase. Then in hbase-site.xml, set - dfs.client.read.shortcircuit to be true - - + dfsclient will complain if open to other than the hbase user. + If you are running on an old Hadoop, one that is without HDFS-347 but that has + HDFS-2246, you + must set two configurations. First, the hdfs-site.xml needs to be amended. Set the property + dfs.block.local-path-access.user to be the only + user that can use the shortcut. This has to be the user that started HBase. Then in + hbase-site.xml, set dfs.client.read.shortcircuit to be + true + Services -- at least the HBase RegionServers -- will need to be restarted in order to pick up the new configurations. About This Guide This reference guide is a work in progress. The source for this guide can be found in the src/main/docbkx directory of the HBase source. This reference - guide is marked up using DocBook from + guide is marked up using DocBook from which the the finished guide is generated as part of the 'site' build target. Run mvn site to generate this documentation. Amendments and improvements to the documentation are welcomed. Click <preamble> - <MAGIC 4 byte integer> <1 byte RPC Format Version> <1 byte auth type> We need the auth method spec. here so the connection header is encoded if auth enabled. + <MAGIC 4 byte integer> <1 byte RPC Format Version> <1 byte auth type> + We need the auth method spec. here so the connection header is encoded if auth enabled. E.g.: HBas0x000x50 -- 4 bytes of MAGIC -- ‘HBas’ -- plus one-byte of version, 0 in this case, and one byte, 0x50 (SIMPLE). of an auth type. http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/security.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/security.xml b/src/main/docbkx/security.xml index 4fe5aa0..c74af9b 100644 --- a/src/main/docbkx/security.xml +++ b/src/main/docbkx/security.xml @@ -32,11 +32,9 @@

Secure Client Access to Apache HBase - Newer releases of Apache HBase (>= 0.92) support optional SASL authentication of clients - See also Matteo Bertozzi's article on Newer releases of Apache HBase (>= 0.92) support optional SASL authentication of clients. See also Matteo Bertozzi's article on Understanding User Authentication and Authorization in Apache HBase. - . This describes how to set up Apache HBase and clients for connection to secure HBase resources. @@ -339,11 +337,9 @@ grant 'rest_server', 'RWCA'

Simple User Access to Apache HBase - Newer releases of Apache HBase (>= 0.92) support optional SASL authentication of clients - See also Matteo Bertozzi's article on Newer releases of Apache HBase (>= 0.92) support optional SASL authentication of clients. See also Matteo Bertozzi's article on Understanding User Authentication and Authorization in Apache HBase. - . This describes how to set up Apache HBase and clients for simple user access to HBase resources. http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/troubleshooting.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/troubleshooting.xml b/src/main/docbkx/troubleshooting.xml index ec6c1cf..f48e26f 100644 --- a/src/main/docbkx/troubleshooting.xml +++ b/src/main/docbkx/troubleshooting.xml @@ -233,19 +233,16 @@ export SERVER_GC_OPTS="$SERVER_GC_OPTS -XX:NewSize=64m -XX:MaxNewSize=64m"

Mailing Lists - Ask a question on the Apache HBase mailing lists. - The 'dev' mailing list is aimed at the community of developers actually building Apache - HBase and for features currently under development, and 'user' is generally used for - questions on released versions of Apache HBase. Before going to the mailing list, make sure - your question has not already been answered by searching the mailing list archives first. - Use . Take some time crafting your question - See Getting Answers - ; a quality question that includes all context and exhibits evidence the author - has tried to find answers in the manual and out on lists is more likely to get a prompt - response. + Ask a question on the Apache + HBase mailing lists. The 'dev' mailing list is aimed at the community of developers + actually building Apache HBase and for features currently under development, and 'user' is + generally used for questions on released versions of Apache HBase. Before going to the + mailing list, make sure your question has not already been answered by searching the mailing + list archives first. Use . Take some time + crafting your question. See Getting Answers for ideas on crafting good questions. A quality question that + includes all context and exhibits evidence the author has tried to find answers in the + manual and out on lists is more likely to get a prompt response.

http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/upgrading.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/upgrading.xml b/src/main/docbkx/upgrading.xml index 2ba0143..b0a248b 100644 --- a/src/main/docbkx/upgrading.xml +++ b/src/main/docbkx/upgrading.xml @@ -71,12 +71,10 @@ out the jars of one version and replace them with the jars of another, compatible version and all will just work. Unless otherwise specified, HBase point versions are binary compatible. You can safely do rolling upgrades between binary compatible - versions; i.e. across point versions: e.g. from 0.94.5 to 0.94.6 - See Does compatibility between versions also mean binary compatibility? discussion on the hbaes dev mailing list. - .

@@ -506,12 +504,10 @@ Successfully completed Log splitting to change this (The 'normal'/default value is 64MB (67108864)). Run the script bin/set_meta_memstore_size.rb. This will make the necessary edit to your .META. schema. Failure to run this change will make for - a slow cluster - See HBASE-3499 Users upgrading to 0.90.0 need to have their .META. table updated with the right MEMSTORE_SIZE - .

http://git-wip-us.apache.org/repos/asf/hbase/blob/28164872/src/main/docbkx/zookeeper.xml ---------------------------------------------------------------------- diff --git a/src/main/docbkx/zookeeper.xml b/src/main/docbkx/zookeeper.xml index 9f34a8f..206ccf5 100644 --- a/src/main/docbkx/zookeeper.xml +++ b/src/main/docbkx/zookeeper.xml @@ -52,12 +52,10 @@ hbase.zookeeper.property.clientPort property. For all default values used by HBase, including ZooKeeper configuration, see . Look for the - hbase.zookeeper.property prefix - For the full list of ZooKeeper configurations, see ZooKeeper's + hbase.zookeeper.property prefix. For the full list of ZooKeeper configurations, see ZooKeeper's zoo.cfg. HBase does not ship with a zoo.cfg so you will need to browse the conf directory in an appropriate ZooKeeper download. - You must at least list the ensemble servers in hbase-site.xml using the hbase.zookeeper.quorum property. This property defaults to a single