Preparing clusters for Hive replication policies

Before you create a Hive replication policy, you must verify whether Cloudera Private Cloud Data Services Replication Manager supports the clusters for replication, the required ports are open, and the clusters for replication are added in the Management Console. You can also enable Kerberos authentication for clusters supporting Kerberos.

Complete the following checklist to ensure that the clusters are ready to be used in a Hive replication policy:

Have you configured the all-database, table, column Ranger policy for the hdfs user on the target cluster to perform all the operations on all databases and tables?
The hdfs user role is used to import Hive Metastore and must have access to all Hive datasets, including all operations. Otherwise, Hive import fails during the replication process. On the target cluster, the hive user must have Ranger admin privileges. The same hive user performs the metadata import operation.
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To provide access, go to the Ranger Admin UI > Service Manager > Hadoop_SQL Policies > Access section, and provide hdfs user permission to the all-database, table, column policy name.
Have you added the source and target clusters on the Management Console > Clusters page?
For more information, see Adding clusters to a Cloudera Private Cloud Data Services deployment.
important
Consider the following limitations before you add clusters:
- Only users with admin and poweruser roles can add clusters to use in Replication Manager.
- When Auto-TLS is enabled for a cluster, you must use the Cloudera Manager hostname to add a cluster.
- If a Cloudera Manager instance manages multiple clusters, you cannot include those clusters for replication in Cloudera Private Cloud Data Services Replication Manager.
Is the Hive Warehouse Directory enabled for snapshots to use in Hive replication policies?
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Perform the following steps to accomplish this task:
1. Search for hive.metastore.warehouse.dir on the Cloudera Manager > Hive service > Configuration tab.
2. Enter the Hive warehouse directory path that is located in the HDFS file system for the Hive Warehouse Directory property. By default, the Hive warehouse directory is located in the /user/hive/warehouse location.
Are the directories hosting the external tables that are not stored in the Hive warehouse directory snapshottable?
A directory is snapshottable if it has been enabled for snapshots, or because a parent directory is enabled for snapshots. Subdirectories of a snapshottable directory are included in the snapshot.
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To enable snapshots for an HDFS directory, click Enable Snapshots for the required directory on the Cloudera Manager > Clusters > HDFS Service > File Browser tab.

Are the following ports open and available for Replication Manager?


Port	Service	Description
7180 or 7183	Cloudera Manager Admin Console HTTP	Open on the source cluster to enable source Cloudera Manager to communicate with the target Cloudera Manager.
80 or 443	Data transfer from secondary node for AWS / ADLS Gen2	Outgoing port. Open on all the HDFS nodes for AWS and ADLS Gen2.

Are the following additional configurations configured? You can configure one or all of the configurations as necessary.
1. If your cluster has Hive clients installed on hosts with limited resources and the replication policies use these hosts to run the commands, the replication performance might degrade. To improve performance, you can specify the hosts (an “allowlist” ) that can be used during the replication process so that the lower-resource hosts are not used. To specify the hosts, perform the following steps:
  1. Go to the Cloudera Manager > Clusters > Hive service > Configuration page.
  2. Locate the Hive Replication Environment Advanced Configuration Snippet (Safety Valve) property.
  3. Add the HOST_WHITELIST property, and enter a comma-separated list of hostnames to use for Hive/Impala replication.
    For example, HOST_WHITELIST=host-1.mycompany.com,host-2.mycompany.com.
  4. Click Save Changes.
  5. Restart the Hive service.
2. If the Hive Metastore is constantly updated, by activities such as creating or deleting databases or tables, you might want to configure the following properties to optimize replication performance:
  1. Go to the Cloudera Manager > Clusters > Hive service > Configuration page for the source cluster.
  2. Search for the HDFS Client Advanced Configuration Snippet (Safety Valve) for hdfs-site.xml property.
  3. Add the following key-value pairs:
    - Name = replication.hive.ignoreDatabaseNotFound; Value = true
    - Name = replication.hive.ignoreTableNotFound; Value = true
  4. Click Save Changes.
  5. Restart the HDFS service.
3. Hive replication policies replicate parameters of databases, tables, partitions, and indexes by default. Perform the following steps to disable replication of parameters:
  1. Go to the Cloudera Manager > Clusters > Hive service > Configuration page for the source cluster.
  2. Search for Hive Replication Environment Advanced Configuration Snippet property.
  3. Add the following key-value pair:
    Name = REPLICATE_PARAMETERS; Value = false
  4. Click Save Changes.
  5. Restart the Hive service.
Do the clusters support Kerberos?
1. Enable Kerberos authentication and configure additional settings on the clusters to enable replication. Perform the following steps to accomplish this task:
  1. Enable Kerberos authentication. For more information, see Enabling Kerberos authentication for Cloudera.
  2. Enable replication between clusters using Kerberos authentication. For more information, see Configuring kerberized clusters for replication.
2. Add the destination principal as a proxy user on the source cluster if you are using different Kerberos principals for the source and destination clusters.
  For example, if you are using the hdfssrc principal on the source cluster and the hdfsdest principal on the destination cluster, add the following key-value pairs to the HDFS service Cluster-wide Advanced Configuration Snippet (Safety Valve) for core-site.xml property on the source cluster and then restart the HDFS service:
  - Name = hadoop.proxyuser.hdfsdest.groups; Value = *
  - Name = hadoop.proxyuser.hdfsdest.hosts; Value = *
Do you need to replicate data securely? If so, ensure that the SSL/TLS certificate exchange between two Cloudera Manager instances that manage source and target clusters respectively is configured. For more information, see Configuring SSL/TLS certificate exchange between two Cloudera Manager instances.