:original_name: mrs_01_1575.html

.. _mrs_01_1575:

HA
==

Scenarios
---------

The Flink HA mode depends on ZooKeeper. Therefore, ZooKeeper-related configuration items must be set.

Configuration Description
-------------------------

Configuration items include the ZooKeeper address, path, and security certificate.

.. _mrs_01_1575__ta903d6a9c6d24f72abdf46625096cd8c:

.. table:: **Table 1** Parameters

   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | Parameter                                             | Description                                                                                                                                                  | Default Value                                                                          | Mandatory       |
   +=======================================================+==============================================================================================================================================================+========================================================================================+=================+
   | high-availability                                     | Whether HA is enabled. Only the following two modes are supported currently:                                                                                 | zookeeper                                                                              | No              |
   |                                                       |                                                                                                                                                              |                                                                                        |                 |
   |                                                       | #. none: Only a single JobManager is running. The checkpoint is disabled for JobManager.                                                                     |                                                                                        |                 |
   |                                                       | #. ZooKeeper:                                                                                                                                                |                                                                                        |                 |
   |                                                       |                                                                                                                                                              |                                                                                        |                 |
   |                                                       |    -  In non-Yarn mode, multiple JobManagers are supported and the leader JobManager is elected.                                                             |                                                                                        |                 |
   |                                                       |    -  In Yarn mode, only one JobManager exists.                                                                                                              |                                                                                        |                 |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.zookeeper.quorum                    | ZooKeeper quorum address.                                                                                                                                    | Automatic configuration                                                                | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.zookeeper.path.root                 | Root directory that Flink creates on ZooKeeper, storing metadata required in HA mode.                                                                        | /flink                                                                                 | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.storageDir                          | Directory for storing JobManager metadata of state backend. ZooKeeper stores only pointers to actual data.                                                   | hdfs:///flink/recovery                                                                 | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.zookeeper.client.session-timeout    | Session timeout duration on the ZooKeeper client. The unit is millisecond.                                                                                   | 60000                                                                                  | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.zookeeper.client.connection-timeout | Connection timeout duration on the ZooKeeper client. The unit is millisecond.                                                                                | 15000                                                                                  | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.zookeeper.client.retry-wait         | Retry waiting time on the ZooKeeper client. The unit is millisecond.                                                                                         | 5000                                                                                   | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.zookeeper.client.max-retry-attempts | Maximum retry times on the ZooKeeper client.                                                                                                                 | 3                                                                                      | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.job.delay                           | Delay of job restart when JobManager recovers.                                                                                                               | The default value is the same as the value of **akka.ask.timeout**.                    | No              |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | high-availability.zookeeper.client.acl                | ACL (open creator) of the ZooKeeper node. For ACL options, see https://zookeeper.apache.org/doc/r3.5.1-alpha/zookeeperProgrammers.html#sc_BuiltinACLSchemes. | This parameter is configured automatically according to the cluster installation mode. | Yes             |
   |                                                       |                                                                                                                                                              |                                                                                        |                 |
   |                                                       |                                                                                                                                                              | -  Security mode: The default value is **creator**.                                    |                 |
   |                                                       |                                                                                                                                                              | -  Non-security mode: The default value is **open**.                                   |                 |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | zookeeper.sasl.disable                                | Simple authentication and security layer (SASL)-based certificate enable switch.                                                                             | This parameter is configured automatically according to the cluster installation mode. | Yes             |
   |                                                       |                                                                                                                                                              |                                                                                        |                 |
   |                                                       |                                                                                                                                                              | -  Security mode: The default value is **false**.                                      |                 |
   |                                                       |                                                                                                                                                              | -  Non-security mode: The default value is **true**.                                   |                 |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+
   | zookeeper.sasl.service-name                           | -  If the ZooKeeper server configures a service whose name is different from **ZooKeeper**, this configuration item can be set.                              | zookeeper                                                                              | Yes             |
   |                                                       | -  If service names on the client and server are inconsistent, authentication fails.                                                                         |                                                                                        |                 |
   +-------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------+-----------------+

.. note::

   For versions earlier than MRS 3.x, the **high-availability.job.delay** parameter is not supported.