Just as in Hadoop where you add site-specific HDFS configuration
to the hdfs-site.xml
file,
for HBase, site specific customizations go into
the file conf/hbase-site.xml
.
For the list of configurable properties, see
Section 1.6.1.1, “HBase Default Configuration”
below or view the raw hbase-default.xml
source file in the HBase source code at
src/main/resources
.
Not all configuration options make it out to
hbase-default.xml
. Configuration
that it is thought rare anyone would change can exist only
in code; the only way to turn up such configurations is
via a reading of the source code itself.
Currently, changes here will require a cluster restart for HBase to notice the change.
The documentation below is generated using the default hbase configuration file,
hbase-default.xml
, as source.
hbase.rootdir
The directory shared by region servers and into which HBase persists. The URL should be 'fully-qualified' to include the filesystem scheme. For example, to specify the HDFS directory '/hbase' where the HDFS instance's namenode is running at namenode.example.org on port 9000, set this value to: hdfs://namenode.example.org:9000/hbase. By default HBase writes into /tmp. Change this configuration else all data will be lost on machine restart.
Default: file:///tmp/hbase-${user.name}/hbase
hbase.master.port
The port the HBase Master should bind to.
Default: 60000
hbase.cluster.distributed
The mode the cluster will be in. Possible values are false for standalone mode and true for distributed mode. If false, startup will run all HBase and ZooKeeper daemons together in the one JVM.
Default: false
hbase.tmp.dir
Temporary directory on the local filesystem. Change this setting to point to a location more permanent than '/tmp' (The '/tmp' directory is often cleared on machine restart).
Default: /tmp/hbase-${user.name}
hbase.master.info.port
The port for the HBase Master web UI. Set to -1 if you do not want a UI instance run.
Default: 60010
hbase.master.info.bindAddress
The bind address for the HBase Master web UI
Default: 0.0.0.0
hbase.client.write.buffer
Default size of the HTable clien write buffer in bytes. A bigger buffer takes more memory -- on both the client and server side since server instantiates the passed write buffer to process it -- but a larger buffer size reduces the number of RPCs made. For an estimate of server-side memory-used, evaluate hbase.client.write.buffer * hbase.regionserver.handler.count
Default: 2097152
hbase.regionserver.port
The port the HBase RegionServer binds to.
Default: 60020
hbase.regionserver.info.port
The port for the HBase RegionServer web UI Set to -1 if you do not want the RegionServer UI to run.
Default: 60030
hbase.regionserver.info.port.auto
Whether or not the Master or RegionServer UI should search for a port to bind to. Enables automatic port search if hbase.regionserver.info.port is already in use. Useful for testing, turned off by default.
Default: false
hbase.regionserver.info.bindAddress
The address for the HBase RegionServer web UI
Default: 0.0.0.0
hbase.regionserver.class
The RegionServer interface to use. Used by the client opening proxy to remote region server.
Default: org.apache.hadoop.hbase.ipc.HRegionInterface
hbase.client.pause
General client pause value. Used mostly as value to wait before running a retry of a failed get, region lookup, etc.
Default: 1000
hbase.client.retries.number
Maximum retries. Used as maximum for all retryable operations such as fetching of the root region from root region server, getting a cell's value, starting a row update, etc. Default: 10.
Default: 10
hbase.bulkload.retries.number
Maximum retries. This is maximum number of iterations to atomic bulk loads are attempted in the face of splitting operations 0 means never give up. Default: 0.
Default: 0
hbase.client.scanner.caching
Number of rows that will be fetched when calling next on a scanner if it is not served from (local, client) memory. Higher caching values will enable faster scanners but will eat up more memory and some calls of next may take longer and longer times when the cache is empty. Do not set this value such that the time between invocations is greater than the scanner timeout; i.e. hbase.regionserver.lease.period
Default: 1
hbase.client.keyvalue.maxsize
Specifies the combined maximum allowed size of a KeyValue instance. This is to set an upper boundary for a single entry saved in a storage file. Since they cannot be split it helps avoiding that a region cannot be split any further because the data is too large. It seems wise to set this to a fraction of the maximum region size. Setting it to zero or less disables the check.
Default: 10485760
hbase.regionserver.lease.period
HRegion server lease period in milliseconds. Default is 60 seconds. Clients must report in within this period else they are considered dead.
Default: 60000
hbase.regionserver.handler.count
Count of RPC Listener instances spun up on RegionServers. Same property is used by the Master for count of master handlers. Default is 10.
Default: 10
hbase.regionserver.msginterval
Interval between messages from the RegionServer to Master in milliseconds.
Default: 3000
hbase.regionserver.optionallogflushinterval
Sync the HLog to the HDFS after this interval if it has not accumulated enough entries to trigger a sync. Default 1 second. Units: milliseconds.
Default: 1000
hbase.regionserver.regionSplitLimit
Limit for the number of regions after which no more region splitting should take place. This is not a hard limit for the number of regions but acts as a guideline for the regionserver to stop splitting after a certain limit. Default is set to MAX_INT; i.e. do not block splitting.
Default: 2147483647
hbase.regionserver.logroll.period
Period at which we will roll the commit log regardless of how many edits it has.
Default: 3600000
hbase.regionserver.logroll.errors.tolerated
The number of consecutive WAL close errors we will allow before triggering a server abort. A setting of 0 will cause the region server to abort if closing the current WAL writer fails during log rolling. Even a small value (2 or 3) will allow a region server to ride over transient HDFS errors.
Default: 2
hbase.regionserver.hlog.reader.impl
The HLog file reader implementation.
Default: org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader
hbase.regionserver.hlog.writer.impl
The HLog file writer implementation.
Default: org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogWriter
hbase.regionserver.nbreservationblocks
The number of resevoir blocks of memory release on OOME so we can cleanup properly before server shutdown.
Default: 4
hbase.zookeeper.dns.interface
The name of the Network Interface from which a ZooKeeper server should report its IP address.
Default: default
hbase.zookeeper.dns.nameserver
The host name or IP address of the name server (DNS) which a ZooKeeper server should use to determine the host name used by the master for communication and display purposes.
Default: default
hbase.regionserver.dns.interface
The name of the Network Interface from which a region server should report its IP address.
Default: default
hbase.regionserver.dns.nameserver
The host name or IP address of the name server (DNS) which a region server should use to determine the host name used by the master for communication and display purposes.
Default: default
hbase.master.dns.interface
The name of the Network Interface from which a master should report its IP address.
Default: default
hbase.master.dns.nameserver
The host name or IP address of the name server (DNS) which a master should use to determine the host name used for communication and display purposes.
Default: default
hbase.balancer.period
Period at which the region balancer runs in the Master.
Default: 300000
hbase.regions.slop
Rebalance if any regionserver has average + (average * slop) regions. Default is 20% slop.
Default: 0.2
hbase.master.logcleaner.ttl
Maximum time a HLog can stay in the .oldlogdir directory, after which it will be cleaned by a Master thread.
Default: 600000
hbase.master.logcleaner.plugins
A comma-separated list of LogCleanerDelegate invoked by the LogsCleaner service. These WAL/HLog cleaners are called in order, so put the HLog cleaner that prunes the most HLog files in front. To implement your own LogCleanerDelegate, just put it in HBase's classpath and add the fully qualified class name here. Always add the above default log cleaners in the list.
Default: org.apache.hadoop.hbase.master.TimeToLiveLogCleaner
hbase.regionserver.global.memstore.upperLimit
Maximum size of all memstores in a region server before new updates are blocked and flushes are forced. Defaults to 40% of heap
Default: 0.4
hbase.regionserver.global.memstore.lowerLimit
When memstores are being forced to flush to make room in memory, keep flushing until we hit this mark. Defaults to 35% of heap. This value equal to hbase.regionserver.global.memstore.upperLimit causes the minimum possible flushing to occur when updates are blocked due to memstore limiting.
Default: 0.35
hbase.server.thread.wakefrequency
Time to sleep in between searches for work (in milliseconds). Used as sleep interval by service threads such as log roller.
Default: 10000
hbase.server.versionfile.writeattempts
How many time to retry attempting to write a version file before just aborting. Each attempt is seperated by the hbase.server.thread.wakefrequency milliseconds.
Default: 3
hbase.hregion.memstore.flush.size
Memstore will be flushed to disk if size of the memstore exceeds this number of bytes. Value is checked by a thread that runs every hbase.server.thread.wakefrequency.
Default: 134217728
hbase.hregion.preclose.flush.size
If the memstores in a region are this size or larger when we go to close, run a "pre-flush" to clear out memstores before we put up the region closed flag and take the region offline. On close, a flush is run under the close flag to empty memory. During this time the region is offline and we are not taking on any writes. If the memstore content is large, this flush could take a long time to complete. The preflush is meant to clean out the bulk of the memstore before putting up the close flag and taking the region offline so the flush that runs under the close flag has little to do.
Default: 5242880
hbase.hregion.memstore.block.multiplier
Block updates if memstore has hbase.hregion.block.memstore time hbase.hregion.flush.size bytes. Useful preventing runaway memstore during spikes in update traffic. Without an upper-bound, memstore fills such that when it flushes the resultant flush files take a long time to compact or split, or worse, we OOME.
Default: 2
hbase.hregion.memstore.mslab.enabled
Enables the MemStore-Local Allocation Buffer, a feature which works to prevent heap fragmentation under heavy write loads. This can reduce the frequency of stop-the-world GC pauses on large heaps.
Default: true
hbase.hregion.max.filesize
Maximum HStoreFile size. If any one of a column families' HStoreFiles has grown to exceed this value, the hosting HRegion is split in two. Default: 1G.
Default: 1073741824
hbase.hstore.compactionThreshold
If more than this number of HStoreFiles in any one HStore (one HStoreFile is written per flush of memstore) then a compaction is run to rewrite all HStoreFiles files as one. Larger numbers put off compaction but when it runs, it takes longer to complete.
Default: 3
hbase.hstore.blockingStoreFiles
If more than this number of StoreFiles in any one Store (one StoreFile is written per flush of MemStore) then updates are blocked for this HRegion until a compaction is completed, or until hbase.hstore.blockingWaitTime has been exceeded.
Default: 7
hbase.hstore.blockingWaitTime
The time an HRegion will block updates for after hitting the StoreFile limit defined by hbase.hstore.blockingStoreFiles. After this time has elapsed, the HRegion will stop blocking updates even if a compaction has not been completed. Default: 90 seconds.
Default: 90000
hbase.hstore.compaction.max
Max number of HStoreFiles to compact per 'minor' compaction.
Default: 10
hbase.hregion.majorcompaction
The time (in miliseconds) between 'major' compactions of all HStoreFiles in a region. Default: 1 day. Set to 0 to disable automated major compactions.
Default: 86400000
hbase.mapreduce.hfileoutputformat.blocksize
The mapreduce HFileOutputFormat writes storefiles/hfiles. This is the minimum hfile blocksize to emit. Usually in hbase, writing hfiles, the blocksize is gotten from the table schema (HColumnDescriptor) but in the mapreduce outputformat context, we don't have access to the schema so get blocksize from Configuation. The smaller you make the blocksize, the bigger your index and the less you fetch on a random-access. Set the blocksize down if you have small cells and want faster random-access of individual cells.
Default: 65536
hfile.block.cache.size
Percentage of maximum heap (-Xmx setting) to allocate to block cache used by HFile/StoreFile. Default of 0.25 means allocate 25%. Set to 0 to disable but it's not recommended.
Default: 0.25
hbase.hash.type
The hashing algorithm for use in HashFunction. Two values are supported now: murmur (MurmurHash) and jenkins (JenkinsHash). Used by bloom filters.
Default: murmur
hfile.block.index.cacheonwrite
This allows to put non-root multi-level index blocks into the block cache at the time the index is being written.
Default: false
hfile.index.block.max.size
When the size of a leaf-level, intermediate-level, or root-level index block in a multi-level block index grows to this size, the block is written out and a new block is started.
Default: 131072
hfile.format.version
The HFile format version to use for new files. Set this to 1 to test backwards-compatibility. The default value of this option should be consistent with FixedFileTrailer.MAX_VERSION.
Default: 2
io.storefile.bloom.block.size
The size in bytes of a single block ("chunk") of a compound Bloom filter. This size is approximate, because Bloom blocks can only be inserted at data block boundaries, and the number of keys per data block varies.
Default: 131072
io.storefile.bloom.cacheonwrite
Enables cache-on-write for inline blocks of a compound Bloom filter.
Default: false
hbase.rs.cacheblocksonwrite
Whether an HFile block should be added to the block cache when the block is finished.
Default: false
hbase.rpc.engine
Implementation of org.apache.hadoop.hbase.ipc.RpcEngine to be used for client / server RPC call marshalling.
Default: org.apache.hadoop.hbase.ipc.WritableRpcEngine
hbase.master.keytab.file
Full path to the kerberos keytab file to use for logging in the configured HMaster server principal.
Default:
hbase.master.kerberos.principal
Ex. "hbase/_HOST@EXAMPLE.COM". The kerberos principal name that should be used to run the HMaster process. The principal name should be in the form: user/hostname@DOMAIN. If "_HOST" is used as the hostname portion, it will be replaced with the actual hostname of the running instance.
Default:
hbase.regionserver.keytab.file
Full path to the kerberos keytab file to use for logging in the configured HRegionServer server principal.
Default:
hbase.regionserver.kerberos.principal
Ex. "hbase/_HOST@EXAMPLE.COM". The kerberos principal name that should be used to run the HRegionServer process. The principal name should be in the form: user/hostname@DOMAIN. If "_HOST" is used as the hostname portion, it will be replaced with the actual hostname of the running instance. An entry for this principal must exist in the file specified in hbase.regionserver.keytab.file
Default:
hadoop.policy.file
The policy configuration file used by RPC servers to make authorization decisions on client requests. Only used when HBase security is enabled.
Default: hbase-policy.xml
hbase.superuser
List of users or groups (comma-separated), who are allowed full privileges, regardless of stored ACLs, across the cluster. Only used when HBase security is enabled.
Default:
hbase.auth.key.update.interval
The update interval for master key for authentication tokens in servers in milliseconds. Only used when HBase security is enabled.
Default: 86400000
hbase.auth.token.max.lifetime
The maximum lifetime in milliseconds after which an authentication token expires. Only used when HBase security is enabled.
Default: 604800000
zookeeper.session.timeout
ZooKeeper session timeout. HBase passes this to the zk quorum as suggested maximum time for a session (This setting becomes zookeeper's 'maxSessionTimeout'). See http://hadoop.apache.org/zookeeper/docs/current/zookeeperProgrammers.html#ch_zkSessions "The client sends a requested timeout, the server responds with the timeout that it can give the client. " In milliseconds.
Default: 180000
zookeeper.znode.parent
Root ZNode for HBase in ZooKeeper. All of HBase's ZooKeeper files that are configured with a relative path will go under this node. By default, all of HBase's ZooKeeper file path are configured with a relative path, so they will all go under this directory unless changed.
Default: /hbase
zookeeper.znode.rootserver
Path to ZNode holding root region location. This is written by the master and read by clients and region servers. If a relative path is given, the parent folder will be ${zookeeper.znode.parent}. By default, this means the root location is stored at /hbase/root-region-server.
Default: root-region-server
zookeeper.znode.acl.parent
Root ZNode for access control lists.
Default: acl
hbase.coprocessor.region.classes
A comma-separated list of Coprocessors that are loaded by default on all tables. For any override coprocessor method, these classes will be called in order. After implementing your own Coprocessor, just put it in HBase's classpath and add the fully qualified class name here. A coprocessor can also be loaded on demand by setting HTableDescriptor.
Default:
hbase.coprocessor.master.classes
A comma-separated list of org.apache.hadoop.hbase.coprocessor.MasterObserver coprocessors that are loaded by default on the active HMaster process. For any implemented coprocessor methods, the listed classes will be called in order. After implementing your own MasterObserver, just put it in HBase's classpath and add the fully qualified class name here.
Default:
hbase.zookeeper.quorum
Comma separated list of servers in the ZooKeeper Quorum. For example, "host1.mydomain.com,host2.mydomain.com,host3.mydomain.com". By default this is set to localhost for local and pseudo-distributed modes of operation. For a fully-distributed setup, this should be set to a full list of ZooKeeper quorum servers. If HBASE_MANAGES_ZK is set in hbase-env.sh this is the list of servers which we will start/stop ZooKeeper on.
Default: localhost
hbase.zookeeper.peerport
Port used by ZooKeeper peers to talk to each other. See http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperStarted.html#sc_RunningReplicatedZooKeeper for more information.
Default: 2888
hbase.zookeeper.leaderport
Port used by ZooKeeper for leader election. See http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperStarted.html#sc_RunningReplicatedZooKeeper for more information.
Default: 3888
hbase.zookeeper.property.initLimit
Property from ZooKeeper's config zoo.cfg. The number of ticks that the initial synchronization phase can take.
Default: 10
hbase.zookeeper.property.syncLimit
Property from ZooKeeper's config zoo.cfg. The number of ticks that can pass between sending a request and getting an acknowledgment.
Default: 5
hbase.zookeeper.property.dataDir
Property from ZooKeeper's config zoo.cfg. The directory where the snapshot is stored.
Default: ${hbase.tmp.dir}/zookeeper
hbase.zookeeper.property.clientPort
Property from ZooKeeper's config zoo.cfg. The port at which the clients will connect.
Default: 2181
hbase.zookeeper.property.maxClientCnxns
Property from ZooKeeper's config zoo.cfg. Limit on number of concurrent connections (at the socket level) that a single client, identified by IP address, may make to a single member of the ZooKeeper ensemble. Set high to avoid zk connection issues running standalone and pseudo-distributed.
Default: 300
hbase.rest.port
The port for the HBase REST server.
Default: 8080
hbase.rest.readonly
Defines the mode the REST server will be started in. Possible values are: false: All HTTP methods are permitted - GET/PUT/POST/DELETE. true: Only the GET method is permitted.
Default: false
hbase.defaults.for.version.skip
Set to true to skip the 'hbase.defaults.for.version' check. Setting this to true can be useful in contexts other than the other side of a maven generation; i.e. running in an ide. You'll want to set this boolean to true to avoid seeing the RuntimException complaint: "hbase-default.xml file seems to be for and old version of HBase (@@@VERSION@@@), this version is X.X.X-SNAPSHOT"
Default: false
hbase.coprocessor.abortonerror
Set to true to cause the hosting server (master or regionserver) to abort if a coprocessor throws a Throwable object that is not IOException or a subclass of IOException. Setting it to true might be useful in development environments where one wants to terminate the server as soon as possible to simplify coprocessor failure analysis.
Default: false
hbase.online.schema.update.enable
Set true to enable online schema changes. This is an experimental feature. There are known issues modifying table schemas at the same time a region split is happening so your table needs to be quiescent or else you have to be running with splits disabled.
Default: false
dfs.support.append
Does HDFS allow appends to files? This is an hdfs config. set in here so the hdfs client will do append support. You must ensure that this config. is true serverside too when running hbase (You will have to restart your cluster after setting it).
Default: true
hbase.offheapcache.percentage
The amount of off heap space to be allocated towards the experimental off heap cache. If you desire the cache to be disabled, simply set this value to 0.
Default: 0
Set HBase environment variables in this file.
Examples include options to pass the JVM on start of
an HBase daemon such as heap size and garbarge collector configs.
You can also set configurations for HBase configuration, log directories,
niceness, ssh options, where to locate process pid files,
etc. Open the file at
conf/hbase-env.sh
and peruse its content.
Each option is fairly well documented. Add your own environment
variables here if you want them read by HBase daemons on startup.
Changes here will require a cluster restart for HBase to notice the change.
Edit this file to change rate at which HBase files are rolled and to change the level at which HBase logs messages.
Changes here will require a cluster restart for HBase to notice the change though log levels can be changed for particular daemons via the HBase UI.
Since the HBase Master may move around, clients bootstrap by looking to ZooKeeper for
current critical locations. ZooKeeper is where all these values are kept. Thus clients
require the location of the ZooKeeper ensemble information before they can do anything else.
Usually this the ensemble location is kept out in the hbase-site.xml
and
is picked up by the client from the CLASSPATH
.
If you are configuring an IDE to run a HBase client, you should
include the conf/
directory on your classpath so
hbase-site.xml
settings can be found (or
add src/test/resources
to pick up the hbase-site.xml
used by tests).
Minimally, a client of HBase needs the hbase, hadoop, log4j, commons-logging, commons-lang,
and ZooKeeper jars in its CLASSPATH
connecting to a cluster.
An example basic hbase-site.xml
for client only
might look as follows:
<?xml version="1.0"?> <?xml-stylesheet type="text/xsl" href="configuration.xsl"?> <configuration> <property> <name>hbase.zookeeper.quorum</name> <value>example1,example2,example3</value> <description>The directory shared by region servers. </description> </property> </configuration>
The configuration used by a Java client is kept
in an HBaseConfiguration instance.
The factory method on HBaseConfiguration, HBaseConfiguration.create();
,
on invocation, will read in the content of the first hbase-site.xml
found on
the client's CLASSPATH
, if one is present
(Invocation will also factor in any hbase-default.xml
found;
an hbase-default.xml ships inside the hbase.X.X.X.jar
).
It is also possible to specify configuration directly without having to read from a
hbase-site.xml
. For example, to set the ZooKeeper
ensemble for the cluster programmatically do as follows:
Configuration config = HBaseConfiguration.create(); config.set("hbase.zookeeper.quorum", "localhost"); // Here we are running zookeeper locally
If multiple ZooKeeper instances make up your ZooKeeper ensemble,
they may be specified in a comma-separated list (just as in the hbase-site.xml
file).
This populated Configuration
instance can then be passed to an
HTable,
and so on.