Migrate Drill to Run Under YARN

As of Drill 1.8, you can migrate Drill to run under YARN instead of the MapR Warden service. When you migrate Drill to run under YARN, you must back up configurations, including files and storage plugins, shutdown the Drill cluster running under Warden, and uninstall Drill on all Drill nodes in the cluster. You may also want to determine which system settings have been changed from the Drill defaults.

NOTE: Drill-on-YARN is an advanced feature used to manage a production Drill cluster. Only skilled Drill and MapR administrators, familiar with YARN, should configure Drill to run under YARN. If you are new to Drill, consider running Drill under the MapR Warden service until you are familiar with Drill and Drill cluster management.

The sections below provide the tasks required to migrate Drill under YARN:

Tasks

Complete the following tasks when you want to migrate Drill to run under YARN:

Backup configurations and UDFs

Back up congfiguration files, storage plugin configurations, and UDFs (user-defined functions) or custom JAR files. Back up the configuration files located in /opt/mapr/drill/drill-<version>/conf, including drill-override.conf and drill-env.sh, to preserve your ZooKeeper configuration and any options or custom configurations specified in the files. Also back up logback.xml if you configured the file for the Lilith software.

To back up configuration files, go to /opt/mapr/drill/drill-<version>/conf, and copy the files to a location outside of the Drill installation directory.
```
cp <file_name> drill-env.sh /path/to/directory
```
To back up custom JARs or UDFs, go to /opt/mapr/drill/drill-<version>/jars/3rdparty and copy the JARs ro UDFs to a location outside of the Drill installation directory.
To back up storage plugin configurations, complete the following steps:
1. Start the Web Console. The Drill node that you use to access the Web Console must be a node that is currently running the Drillbit process.
2. Click Storage.
3. Click Update next to a storage plugin.
4. Copy the configuration to a text file, and save the file.
5. Repeat steps 3 and 4 for each storage plugin configuration that you want to save.

Verify system option settings

Drill should save set system options when you migrate Drill. However, you may want to verify which system options were changed from the default settings beforehand. You can run the following query to see which system options were changed from the defaults:

select * from sys.options where status = 'CHANGED';

Example:

select * from sys.options where status = 'CHANGED';
+-------------------------------------+----------+---------+----------+----------+-------------+-----------+------------+
|                name                 |   kind   |  type   |  status  | num_val  | string_val  | bool_val  | float_val  |
+-------------------------------------+----------+---------+----------+----------+-------------+-----------+------------+
| exec.errors.verbose                 | BOOLEAN  | SYSTEM  | CHANGED  | null     | null        | true      | null       |
| new_view_default_permissions        | STRING   | SYSTEM  | CHANGED  | null     | 777         | null      | null       |
| planner.enable_decimal_data_type    | BOOLEAN  | SYSTEM  | CHANGED  | null     | null        | true      | null       |
| planner.enable_limit0_optimization  | BOOLEAN  | SYSTEM  | CHANGED  | null     | null        | true      | null       |
+-------------------------------------+----------+---------+----------+----------+-------------+-----------+------------+
4 rows selected (0.541 seconds)

After you migrate, run the query again to verify that the system options are still set. If not, set the options.

Shutdown the Drill cluster

Issue the following command to shutdown the existing Warden-managed Drill cluster:

maprcli node services -name drill-bits -action stop -nodes <node host names separated by a space>

NOTE: Do not shutdown nodes when queries are in progress.

Verify that Drillbits stopped

Run the following command to verify that the Drillbit service is no longer running on each node:

ps -ef | grep -i drill

No Drill processes should print to screen when you run this command.

You can also log in to the MCS at https://<host name>:8443 to verify the status of the Drillbit service. You should not see Drillbit as a listed service.

Uninstall Drill

Uninstall Drill and then run configure.sh -R to refresh the configuration.

Issue the command appropriate for your system as root or using sudo to uninstall the mapr-drill package:

Operating System	Command
RedHat/CentOS	`yum remove mapr-drill`
Ubuntu	`apt-get remove mapr-drill`

NOTE: Verify that Drillbit processes stopped.