Elasticsearch:Perform a check before a version upgrade

If you want to upgrade the version of a cluster from V5.X to V6.X, you must also perform the following operations:

• Split each multi-type index stored in the V5.X cluster into multiple single-type indexes.

  Clusters of V6.X or later do not support multi-type indexes. If the V5.X cluster stores multi-type indexes, you can write data to the indexes after the cluster version is upgraded to V6.X. However, if you create multi-type indexes in V6.X, errors are reported. We recommend that you split each multi-type index into single-type indexes before the upgrade.

• Run the following command to check whether the cross-cluster search feature is enabled for the cluster. If the feature is enabled for the cluster, the search.remote parameter is displayed in the return result, and the value of this parameter is not null.

  GET _cluster/settings

  If the feature is enabled for the cluster, run the following command to disable the feature. After you upgrade the version of the cluster, you can enable the feature again.

  PUT _cluster/settings
  {
    "persistent": {
      "search.remote.*": null
    },
    "transient": {
      "search.remote.*": null
    }
  }

  Important

  The search.remote parameter is used to configure the cross-cluster search feature in V5.X, whereas the cluster.remote parameter is used in V6.X.

When you upgrade the version of your cluster, you must click Precheck to enable the system to check whether the cluster status and cluster load are normal. The version of your cluster can be upgraded only if the cluster is in a normal state and its load is normal. Before you upgrade the version of your cluster, you can also refer to the items listed in the following table to perform a manual check.

When you upgrade the version of a cluster to V6.X, the system automatically checks whether incompatible configurations exist between the versions. If you do not modify the incompatible configurations, your cluster services may be affected after the upgrade. To ensure that the cluster version can be upgraded, you can run the GET _cluster/settings and GET*/_settings?flat_settings=true command to check whether the configurations listed in the following table are configured for your cluster before you perform the upgrade.

This section provides the methods that are used to modify incompatible configurations.

• Cluster-level incompatible configurations

  For cluster-level incompatible configurations, you can disable the configurations.

  Configuration category	Command to disable the configuration
  Snapshot settings	PUT _cluster/settings { "persistent": { "cluster.routing.allocation.snapshot.relocation_enabled": null }, "transient": { "cluster.routing.allocation.snapshot.relocation_enabled": null } }
  Storage throttling settings	PUT _cluster/settings { "persistent": { "indices.store.throttle.type": null, "indices.store.throttle.max_bytes_per_sec": null }, "transient": { "indices.store.throttle.type": null, "indices.store.throttle.max_bytes_per_sec": null } }

• Index-level incompatible configurations

  For index-level incompatible configurations, you can disable the configurations.

  Configuration category	Command to disable the configuration	Additional information
  Similarity settings	PUT test_index/_settings { "index.similarity.base.*": null }	These configurations can be modified only after indexes are closed. You cannot read data from or write data to closed indexes. After the modifications, you can open the indexes. The following example shows how to open and close the test_index index: Close the index POST test_index/_close Open the index POST test_index/_open
  Shadow replica settings	PUT test_index/_settings { "index.shared_filesystem": null, "index.shadow_replicas": null }
  Index storage settings	PUT test_index/_settings { "index.store.type": null }
  Storage throttling settings	PUT test_index/_settings { "settings": { "index.store.throttle.type": null, "index.store.throttle.max_bytes_per_sec": null } }	None.

  Note

  Indexes that have the include_in_all parameter configured can still be used in the later version. You do not need to modify this parameter.

• Index template-level incompatible configurations

  The following example shows how to modify configurations in the test_template index template:

  1. Run the GET _template/test_template command to query the test_template index template.

     The query result shows that the index template contains the following incompatible configurations: index storage settings, _all, and include_in_all.

     {
      "test_template": {
        "order": 0,
        "template": "test_*",
        "settings": {
          "index": {
            "store": {
              "throttle": {
                "max_bytes_per_sec": "100m"
              }
            }
          }
        },
        "mappings": {
          "test_type": {
            "_all": {
              "enabled": true
            },
            "properties": {
              "test_field": {
                "type": "text",
                "include_in_all": true
              }
            }
          }
        },
        "aliases": {}
      }
     }

  2. Run the following command to delete the incompatible configurations and update the index template:

     PUT _template/test_template
     {
        "order": 0,
        "template": "test_*",
        "settings": {
        },
        "mappings": {
          "test_type": {
            "properties": {
              "test_field": {
                "type": "text"
              }
            }
          }
        },
        "aliases": {}
     }