This appendix lists all configuration properties HBase supports with their default values and a description of how they are used. Use it to reference what you need to put into the hbase-site.xml file. The following list is sorted alphabetically for easier lookup. See Configuration for details on how to tune the more important properties.
The description for each property is taken as-is from the hbase-default.xml file. The Type, Default, and Unit fields were added for your convenience.
hbase.balancer.period
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.
hbase.client.pause
General client pause value. Used mostly as value to wait before running a retry of a failed get, region lookup, etc.
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.
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 time 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
.
hbase.client.write.buffer
Default size of the
HTable
client 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
.
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.
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.
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
.
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
RuntimeException complaint
"hbase-default.xml file seems to be for an old version of
HBase (@@@VERSION@@@), this version is
X.X.X-SNAPSHOT"
.
hbase.hash.type
The hashing algorithm for use in
HashFunction
. Two values are supported now:
murmur
(MurmurHash) and jenkins
(JenkinsHash). Used by Bloom filters.
hbase.hregion.majorcompaction
The time (in milliseconds) between major
compactions of all HStoreFile
s in a region.
Default: 1 day. Set to 0 to disable automated major
compactions.
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.
hbase.hregion.memstore.block.multiplier
Block updates if memstore has
hbase.hregion.block.memstore
time hbase.hregion.
flush.size
bytes. Useful for preventing runaway memstore during spikes in update
traffic. Without an upper bound, the memstore fills such that when it
flushes, the resultant flush files take a long time to compact or
split, or worse, we OOME.
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
.
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.
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.
hbase.hstore.blockingStoreFiles
If more than this number of
StoreFile
s 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.
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.
hbase.hstore.compaction.max
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.
hbase.mapreduce.hfileoutputformat.blocksize
The mapreduce
HFileOutputFormat
writes store files/HFiles. This
is the minimum HFile blocksize
to emit. Usually in
HBase, when 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 we get the blocksize
from
the configuation. The smaller you make the
blocksize
, the bigger your index will be and the
less you will fetch on a random access. Set the
blocksize
down if you have small cells and want
faster random access of individual cells.
hbase.master.dns.interface
The name of the network interface from which a master should report its IP address.
hbase.master.dns.nameserver
The hostname or IP address of the name server (DNS) which a master should use to determine the hostname used for communication and display purposes.
hbase.master.info.bindAddress
hbase.master.info.port
The port for the HBase Master web UI. Set to -1 if you do not want a UI instance run.
hbase.master.kerberos.principal
Example: “hbase/[email protected]”. 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.
hbase.master.keytab.file
Full path to the Kerberos keytab file to use for logging in the configured HMaster server principal.
hbase.master.logcleaner.plugins
A comma-separated list of
LogCleanerDelegate
s 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.master.logcleaner.ttl
Maximum time an HLog can stay in the .oldlogdir directory, after which it will be cleaned by a master thread.
hbase.master.port
hbase.regions.slop
Rebalance if any region server has average + (average * slop) regions. Default is 20% slop.
hbase.regionserver.class
The RegionServer interface to use. Used by the client opening proxy to remote region server.
hbase.regionserver.dns.interface
The name of the network interface from which a region server should report its IP address.
hbase.regionserver.dns.nameserver
The hostname or IP address of the name server (DNS) which a region server should use to determine the hostname used by the master for communication and display purposes.
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.
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.
hbase.regionserver.handler.count
Count of RPC Listener instances spun up on RegionServers. The same property is used by the master for count of master handlers.
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.info.bindAddress
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.
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.
hbase.regionserver.kerberos.principal
Example: “hbase/[email protected]”. 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
.
hbase.regionserver.keytab.file
Full path to the Kerberos keytab file to use for logging in the configured HRegionServer server principal.
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.
hbase.regionserver.logroll.period
Period at which we will roll the commit log regardless of how many edits it has.
hbase.regionserver.msginterval
Interval between messages from the RegionServer to the HBase Master in milliseconds.
hbase.regionserver.nbreservationblocks
The number of reservoir blocks of memory released on OOME so we can clean up properly before server shutdown.
hbase.regionserver.optionallogflushinterval
Sync the HLog to the HDFS after this interval if it has not accumulated enough entries to trigger a sync.
hbase.regionserver.port
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
; that is, do not block splitting.
hbase.rest.port
The port for the HBase REST server.
hbase.rest.readonly
Defines the mode the REST server will be
started in. Possible values are false
, which means
all HTTP methods are permitted (GET
,
PUT
, POST
, and
DELETE
); and true
, which means
only the GET
method is permitted.
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.
hbase.rpc.engine
Implementation of
org.apache.hadoop.hbase.ipc.RpcEngine
to be used
for client/server RPC call marshaling.
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.
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).
hbase.zookeeper.dns.interface
The name of the network interface from which a ZooKeeper server should report its IP address.
hbase.zookeeper.dns.nameserver
The hostname or IP address of the name server (DNS) which a ZooKeeper server should use to determine the hostname used by the master for communication and display purposes.
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.
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.
hbase.zookeeper.property.clientPort
Property from ZooKeeper’s zoo.cfg configuration file. The port at which the clients will connect.
hbase.zookeeper.property.dataDir
Property from ZooKeeper’s zoo.cfg configuration file. The directory where the snapshot is stored.
hbase.zookeeper.property.initLimit
Property from ZooKeeper’s zoo.cfg configuration file. The number of ticks that the initial synchronization phase can take.
hbase.zookeeper.property.maxClientCnxns
Property from ZooKeeper’s zoo.cfg configuration file. 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 ZooKeeper connection issues running standalone and pseudodistributed.
hbase.zookeeper.property.syncLimit
Property from ZooKeeper’s zoo.cfg configuration file. The number of ticks that can pass between sending a request and getting an acknowledgment.
hbase.zookeeper.quorum
Comma-separated list of servers in the
ZooKeeper Quorum. For example, by default,
“host1.mydomain.com,host2.mydomain.com,host3.mydomain.com” is set to
localhost for local and pseudodistributed 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
on which we will start/stop ZooKeeper.
hfile.block.cache.size
Percentage of maximum heap
(-Xmx
setting) to allocate to block cache used by
HFile
/StoreFile
. Default of 0.2
means allocate 20%. Set to 0 to disable.
zookeeper.session.timeout
ZooKeeper session timeout. HBase passes this
to the ZooKeeper quorum as the 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.”
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 paths are configured with a relative path, so they will all go under this directory unless changed.
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.
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