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 // Licensed to the Apache Software Foundation (ASF) under one
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 // distributed with this work for additional information
 // regarding copyright ownership.  The ASF licenses this file
 // to you under the Apache License, Version 2.0 (the
 // "License"); you may not use this file except in compliance
 // with the License.  You may obtain a copy of the License at
 //
 //   http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing,
 // software distributed under the License is distributed on an
 // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 // KIND, either express or implied.  See the License for the
 // specific language governing permissions and limitations
 // under the License.

 [[configuration]]
 = Configuring Apache Kudu

 :author: Kudu Team
 :imagesdir: ./images
 :icons: font
 :toc: left
 :toclevels: 3
 :doctype: book
 :backend: html5
 :sectlinks:
 :experimental:

 == Configure Kudu

 === Configuration Basics
 To configure the behavior of each Kudu process, you can pass command-line flags when
 you start it, or read those options from configuration files by passing them using
 one or more `--flagfile=<file>` options. You can even include the
 `--flagfile` option within your configuration file to include other files. Learn more about gflags
 by reading link:https://gflags.github.io/gflags/[its documentation].

 You can place options for masters and tablet servers into the same configuration
 file, and each will ignore options that do not apply.

 Flags can be prefixed with either one or two `-` characters. This
 documentation standardizes on two: `--example_flag`.

 === Discovering Configuration Options
 Only the most common configuration options are documented here. For a more exhaustive
 list of configuration options, see the link:configuration_reference.html[Configuration Reference].

 To see all configuration flags for a given executable, run it with the `--help` option.
 Take care when configuring undocumented flags, as not every possible
 configuration has been tested, and undocumented options are not guaranteed to be
 maintained in future releases.

 [[directory_configuration]]
 === Directory Configurations
 Every Kudu node requires the specification of directory flags. The
 `--fs_wal_dir` configuration indicates where Kudu will place its write-ahead
 logs. The `--fs_metadata_dir` configuration indicates where Kudu will place
 metadata for each tablet. It is recommended, although not necessary, that these
 directories be placed on a high-performance drives with high bandwidth and low
 latency, e.g. solid-state drives. If `--fs_metadata_dir` is not specified,
 metadata will be placed in the directory specified by `--fs_wal_dir`. Since
 a Kudu node cannot tolerate the loss of its WAL or metadata directories, it
 may be wise to mirror the drives containing these directories in order to
 make recovering from a drive failure easier; however, mirroring may increase
 the latency of Kudu writes.

 The `--fs_data_dirs` configuration indicates where Kudu will write its data
 blocks. This is a comma-separated list of directories; if multiple values are
 specified, data will be striped across the directories. If not specified, data
 blocks will be placed in the directory specified by `--fs_wal_dir`. Note that
 while a single data directory backed by a RAID-0 array will outperform a single
 data directory backed by a single storage device, it is better to let Kudu
 manage its own striping over multiple devices rather than delegating the
 striping to a RAID-0 array.

 Additionally, `--fs_wal_dir` and `--fs_metadata_dir` may be the same as _one
 of_ the directories listed in `--fs_data_dirs`, but must not be sub-directories
 of any of them.

 WARNING: Each directory specified by a configuration flag on a given machine
 should be used by at most one Kudu process. If multiple Kudu processes on the
 same machine are configured to use the same directory, Kudu may refuse to start
 up.

 WARNING: Once `--fs_data_dirs` is set, extra tooling is required to change it.
 For more details, see the link:administration.html#change_dir_config[Kudu
 Administration docs].

 NOTE: The `--fs_wal_dir` and `--fs_metadata_dir` configurations can be changed,
 provided the contents of the directories are also moved to match the flags.

 === Configuring the Kudu Master
 To see all available configuration options for the `kudu-master` executable, run it
 with the `--help` option:
 ----
 $ kudu-master --help
 ----

 [cols="m,d,m,d"]
 .Supported Configuration Flags for Kudu Masters
 |===
 | Flag      | Valid Options     | Default     | Description

 |--master_addresses | string | localhost |  Comma-separated list of all the RPC
 addresses for Master consensus-configuration. If not specified, assumes a standalone Master.
 |--fs_data_dirs | string | | List of directories where the Master will place its data blocks.
 |--fs_metadata_dir | string | | The directory where the Master will place its tablet metadata.
 |--fs_wal_dir | string | | The directory where the Master will place its write-ahead logs.
 |--log_dir | string | /tmp | The directory to store Master log files.
 |===

 For the full list of flags for masters, see the
 link:configuration_reference.html#kudu-master_supported[Kudu Master Configuration Reference].

 === Configuring Tablet Servers
 To see all available configuration options for the `kudu-tserver` executable,
 run it with the `--help` option:
 ----
 $ kudu-tserver --help
 ----

 .Supported Configuration Flags for Kudu Tablet Servers
 |===
 | Flag      | Valid Options     | Default     | Description

 |--fs_data_dirs | string |  | List of directories where the Tablet Server will place its data blocks.
 |--fs_metadata_dir | string |  | The directory where the Tablet Server will place its tablet metadata.
 |--fs_wal_dir | string | | The directory where the Tablet Server will place its write-ahead logs.
 |--log_dir | string | /tmp | The directory to store Tablet Server log files
 |--tserver_master_addrs | string | `127.0.0.1:7051` |  Comma separated
 addresses of the masters which the tablet server should connect to. The masters
 do not read this flag.
 |--block_cache_capacity_mb | integer | 512 | Maximum amount of memory allocated to the Kudu Tablet Server's block cache.
 |--memory_limit_hard_bytes | integer | 4294967296 | Maximum amount of memory a Tablet Server can consume before it starts rejecting all incoming writes.
 |===

 For the full list of flags for tablet servers, see the
 link:configuration_reference.html#kudu-tserver_supported[Kudu Tablet Server Configuration Reference].

 == Configure Kudu Tables
 Kudu allows certain configurations to be set per table. To configure the behavior of a Kudu table,
 you can set these configurations at table creation, or alter them via the Kudu API or Kudu command
 line tool.

 .Supported Configurable Properties for Kudu Tables
 |===
 | Configuration      | Valid Options     | Default     | Description

 | kudu.table.history_max_age_sec | integer | | Number of seconds to retain history for tablets in this table.
 | kudu.table.maintenance_priority | integer | 0 | Priority level of a table for maintenance.
 |===

 == Next Steps
 - link:quickstart.html[Get Started With Kudu]
 - link:developing.html[Developing Applications With Kudu]
	// Licensed to the Apache Software Foundation (ASF) under one
	// or more contributor license agreements. See the NOTICE file
	// distributed with this work for additional information
	// regarding copyright ownership. The ASF licenses this file
	// to you under the Apache License, Version 2.0 (the
	// "License"); you may not use this file except in compliance
	// with the License. You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing,
	// software distributed under the License is distributed on an
	// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	// KIND, either express or implied. See the License for the
	// specific language governing permissions and limitations
	// under the License.

	[[configuration]]
	= Configuring Apache Kudu

	:author: Kudu Team
	:imagesdir: ./images
	:icons: font
	:toc: left
	:toclevels: 3
	:doctype: book
	:backend: html5
	:sectlinks:
	:experimental:

	== Configure Kudu

	=== Configuration Basics
	To configure the behavior of each Kudu process, you can pass command-line flags when
	you start it, or read those options from configuration files by passing them using
	one or more `--flagfile=<file>` options. You can even include the
	`--flagfile` option within your configuration file to include other files. Learn more about gflags
	by reading link:https://gflags.github.io/gflags/[its documentation].

	You can place options for masters and tablet servers into the same configuration
	file, and each will ignore options that do not apply.

	Flags can be prefixed with either one or two `-` characters. This
	documentation standardizes on two: `--example_flag`.

	=== Discovering Configuration Options
	Only the most common configuration options are documented here. For a more exhaustive
	list of configuration options, see the link:configuration_reference.html[Configuration Reference].

	To see all configuration flags for a given executable, run it with the `--help` option.
	Take care when configuring undocumented flags, as not every possible
	configuration has been tested, and undocumented options are not guaranteed to be
	maintained in future releases.

	[[directory_configuration]]
	=== Directory Configurations
	Every Kudu node requires the specification of directory flags. The
	`--fs_wal_dir` configuration indicates where Kudu will place its write-ahead
	logs. The `--fs_metadata_dir` configuration indicates where Kudu will place
	metadata for each tablet. It is recommended, although not necessary, that these
	directories be placed on a high-performance drives with high bandwidth and low
	latency, e.g. solid-state drives. If `--fs_metadata_dir` is not specified,
	metadata will be placed in the directory specified by `--fs_wal_dir`. Since
	a Kudu node cannot tolerate the loss of its WAL or metadata directories, it
	may be wise to mirror the drives containing these directories in order to
	make recovering from a drive failure easier; however, mirroring may increase
	the latency of Kudu writes.

	The `--fs_data_dirs` configuration indicates where Kudu will write its data
	blocks. This is a comma-separated list of directories; if multiple values are
	specified, data will be striped across the directories. If not specified, data
	blocks will be placed in the directory specified by `--fs_wal_dir`. Note that
	while a single data directory backed by a RAID-0 array will outperform a single
	data directory backed by a single storage device, it is better to let Kudu
	manage its own striping over multiple devices rather than delegating the
	striping to a RAID-0 array.

	Additionally, `--fs_wal_dir` and `--fs_metadata_dir` may be the same as _one
	of_ the directories listed in `--fs_data_dirs`, but must not be sub-directories
	of any of them.

	WARNING: Each directory specified by a configuration flag on a given machine
	should be used by at most one Kudu process. If multiple Kudu processes on the
	same machine are configured to use the same directory, Kudu may refuse to start
	up.

	WARNING: Once `--fs_data_dirs` is set, extra tooling is required to change it.
	For more details, see the link:administration.html#change_dir_config[Kudu
	Administration docs].

	NOTE: The `--fs_wal_dir` and `--fs_metadata_dir` configurations can be changed,
	provided the contents of the directories are also moved to match the flags.

	=== Configuring the Kudu Master
	To see all available configuration options for the `kudu-master` executable, run it
	with the `--help` option:
	----
	$ kudu-master --help
	----

	[cols="m,d,m,d"]
	.Supported Configuration Flags for Kudu Masters
	\|===
	\| Flag \| Valid Options \| Default \| Description

	\|--master_addresses \| string \| localhost \| Comma-separated list of all the RPC
	addresses for Master consensus-configuration. If not specified, assumes a standalone Master.
	\|--fs_data_dirs \| string \| \| List of directories where the Master will place its data blocks.
	\|--fs_metadata_dir \| string \| \| The directory where the Master will place its tablet metadata.
	\|--fs_wal_dir \| string \| \| The directory where the Master will place its write-ahead logs.
	\|--log_dir \| string \| /tmp \| The directory to store Master log files.
	\|===

	For the full list of flags for masters, see the
	link:configuration_reference.html#kudu-master_supported[Kudu Master Configuration Reference].

	=== Configuring Tablet Servers
	To see all available configuration options for the `kudu-tserver` executable,
	run it with the `--help` option:
	----
	$ kudu-tserver --help
	----

	.Supported Configuration Flags for Kudu Tablet Servers
	\|===
	\| Flag \| Valid Options \| Default \| Description

	\|--fs_data_dirs \| string \| \| List of directories where the Tablet Server will place its data blocks.
	\|--fs_metadata_dir \| string \| \| The directory where the Tablet Server will place its tablet metadata.
	\|--fs_wal_dir \| string \| \| The directory where the Tablet Server will place its write-ahead logs.
	\|--log_dir \| string \| /tmp \| The directory to store Tablet Server log files
	\|--tserver_master_addrs \| string \| `127.0.0.1:7051` \| Comma separated
	addresses of the masters which the tablet server should connect to. The masters
	do not read this flag.
	\|--block_cache_capacity_mb \| integer \| 512 \| Maximum amount of memory allocated to the Kudu Tablet Server's block cache.
	\|--memory_limit_hard_bytes \| integer \| 4294967296 \| Maximum amount of memory a Tablet Server can consume before it starts rejecting all incoming writes.
	\|===

	For the full list of flags for tablet servers, see the
	link:configuration_reference.html#kudu-tserver_supported[Kudu Tablet Server Configuration Reference].

	== Configure Kudu Tables
	Kudu allows certain configurations to be set per table. To configure the behavior of a Kudu table,
	you can set these configurations at table creation, or alter them via the Kudu API or Kudu command
	line tool.

	.Supported Configurable Properties for Kudu Tables
	\|===
	\| Configuration \| Valid Options \| Default \| Description

	\| kudu.table.history_max_age_sec \| integer \| \| Number of seconds to retain history for tablets in this table.
	\| kudu.table.maintenance_priority \| integer \| 0 \| Priority level of a table for maintenance.
	\|===

	== Next Steps
	- link:quickstart.html[Get Started With Kudu]
	- link:developing.html[Developing Applications With Kudu]