Period at which the region balancer runs in the master.

Type: int

Default: 300000 (5 mins)

Unit: milliseconds

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.

Type: int

Default: 10485760

Unit: bytes

General client pause value. Used mostly as value to wait before running a retry of a failed get, region lookup, etc.

Type: long

Default: 1000 (1 sec)

Unit: milliseconds

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.

Type: int

Default: 10

Unit: number

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.

Type: int

Default: 1

Unit: number

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.

Type: long

Default: 2097152

Unit: bytes

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.

Type: boolean

Default: false

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.

Type: class names

Default: <empty>

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.

Type: class names

Default: <empty>

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".

Type: boolean

Default: false

The hashing algorithm for use in HashFunction. Two values are supported now: murmur (MurmurHash) and jenkins (JenkinsHash). Used by Bloom filters.

Type: string

Default: murmur

The time (in milliseconds) between major compactions of all HStoreFiles in a region. Default: 1 day. Set to 0 to disable automated major compactions.

Type: long

Default: 86400000 (1 day)

Unit: milliseconds

Maximum HStoreFile size. If any one of a column families’ HStoreFiles has grown to exceed this value, the hosting HRegion is split in two.

Type: long

Default: 268435456 (256 * 1024 * 1024)

Unit: bytes

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.

Type: int

Default: 2

Unit: number

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.

Type: long

Default: 67108864 (1024*1024*64L)

Unit: bytes

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.

Type: boolean

Default: true

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.

Type: long

Default: 5242880 (1024 * 1024 * 5)

Unit: bytes

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.

Type: int

Default: 7, hardcoded: -1

Unit: number

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.

Type: int

Default: 90000

Unit: milliseconds

Max number of HStoreFiles to compact per minor compaction.

Type: int

Default: 10

Unit: number

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.

Type: int

Default: 3, hardcoded: 2

Unit: number

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.

Type: int

Default: 65536

Unit: bytes

The name of the network interface from which a master should report its IP address.

Type: string

Default: “default”

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.

Type: string

Default: “default”

The bind address for the HBase Master web UI.

Type: String

Default: 0.0.0.0

The port for the HBase Master web UI. Set to -1 if you do not want a UI instance run.

Type: int

Default: 60010

Unit: number

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.

Type: string

Default:

Full path to the Kerberos keytab file to use for logging in the configured HMaster server principal.

Type: string

Default:

A comma-separated list of LogCleanerDelegates 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.

Type: string

Default: org.apache.hadoop.hbase.master.TimeToLiveLogCleaner

Maximum time an HLog can stay in the .oldlogdir directory, after which it will be cleaned by a master thread.

Type: long

Default: 600000

Unit: milliseconds

The port the HBase Master should bind to.

Type: int

Default: 60000

Unit: number

Rebalance if any region server has average + (average * slop) regions. Default is 20% slop.

Type:

Default: 0.2

Unit: float (percent)

The RegionServer interface to use. Used by the client opening proxy to remote region server.

Type: class name

Default: org.apache.hadoop.hbase.ipc.HRegionInterface

The name of the network interface from which a region server should report its IP address.

Type: string

Default: “default”

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.

Type: string

Default: “default”

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.

Type: float

Default: 0.35, hardcoded: 0.25

Unit: float (percent)

Maximum size of all memstores in a region server before new updates are blocked and flushes are forced. Defaults to 40% of heap.

Type: float

Default: 0.4

Unit: float (percent)

Count of RPC Listener instances spun up on RegionServers. The same property is used by the master for count of master handlers.

Type: int

Default: 10

Unit: number

The HLog file reader implementation.

Type: class name

Default: org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader

The HLog file writer implementation.

Type: class name

Default: org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogWriter

The address for the HBase RegionServer web UI.

Type: string

Default: 0.0.0.0

The port for the HBase RegionServer web UI. Set to -1 if you do not want the RegionServer UI to run.

Type: int

Default: 60030

Unit: number

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.

Type: boolean

Default: false

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.

Type: string

Default: <empty>

Full path to the Kerberos keytab file to use for logging in the configured HRegionServer server principal.

Type: string

Default: <empty>

HRegion server lease period in milliseconds. Default is 60 seconds. Clients must report in within this period else they are considered dead.

Type: long

Default: 60000 (1 min)

Unit: milliseconds

Period at which we will roll the commit log regardless of how many edits it has.

Type: long

Default: 3600000

Unit: milliseconds

Interval between messages from the RegionServer to the HBase Master in milliseconds.

Type: int

Default: 3000 (3 secs)

Unit: milliseconds

The number of reservoir blocks of memory released on OOME so we can clean up properly before server shutdown.

Type: int

Default: 4

Unit: number

Sync the HLog to the HDFS after this interval if it has not accumulated enough entries to trigger a sync.

Type: long

Default: 1000 (1 sec)

Unit: milliseconds

The port the HBase RegionServer binds to.

Type: int

Default: 60020

Unit: number

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.

Type: int

Default: 2147483647

Unit: number

The port for the HBase REST server.

Type: int

Default: 8080, hardcoded: 9090

Unit: number

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.

Type: boolean

Default: false

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.

Type: string

Default: file:///tmp/hbase-${user.name}/hbase

Implementation of org.apache.hadoop.hbase.ipc.RpcEngine to be used for client/server RPC call marshaling.

Type: class name

Default: org.apache.hadoop.hbase.ipc.WritableRpcEngine

Time to sleep in between searches for work (in milliseconds). Used as sleep interval by service threads such as log roller.

Type: int

Default: 10000 (10 secs)

Unit: milliseconds

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).

Type: string

Default: /tmp/hbase-${user.name}

The name of the network interface from which a ZooKeeper server should report its IP address.

Type: string

Default: “default”

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.

Type: string

Default: “default”

Port used by ZooKeeper for leader election. See http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperStarted.html#sc_RunningReplicatedZooKeeper for more information.

Type: int

Default: 3888

Unit: number

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.

Type: int

Default: 2888

Unit: number

Property from ZooKeeper’s zoo.cfg configuration file. The port at which the clients will connect.

Type: int

Default: 2181

Unit: number

Property from ZooKeeper’s zoo.cfg configuration file. The directory where the snapshot is stored.

Type: string

Default: ${hbase.tmp.dir}/zookeeper

Property from ZooKeeper’s zoo.cfg configuration file. The number of ticks that the initial synchronization phase can take.

Type: int

Default: 10

Unit: number

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.

Type: int

Default: 30

Unit: number

Property from ZooKeeper’s zoo.cfg configuration file. The number of ticks that can pass between sending a request and getting an acknowledgment.

Type: int

Default: 5

Unit: number

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.

Type: string

Default: localhost

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.

Type: float

Default: 0.2

Unit: float (percent)

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.”

Type: int

Default: 180000

Unit: milliseconds

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.

Type: string

Default: /hbase

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.

Type: string

Default: root-region-server