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Community Blog FAQ about Data Migration and Cluster Restart

FAQ about Data Migration and Cluster Restart

Unlock efficient data synchronization and master cluster restart operations with our comprehensive FAQ, ensuring uninterrupted services and optimized performance.

FAQ about data migration and synchronization

How do I synchronize data from ApsaraDB for MongoDB to Alibaba Cloud Elasticsearch?

You can use Monstache to synchronize data from ApsaraDB for MongoDB to Alibaba Cloud Elasticsearch in real time. For more information, see Use Monstache to synchronize data from MongoDB to Alibaba Cloud Elasticsearch in real time.

FAQ about cluster restart

How long is required to restart an Elasticsearch cluster or node?

When you restart an Elasticsearch cluster or node, the system displays the required time. The time is estimated based on the specifications, data structure, and data volume of the cluster or node. In most cases, a few hours are required to restart a cluster. For more information, see Restart a cluster or node.

Does the system restart an Elasticsearch cluster after I enable or disable the Public Network Access feature for the cluster?

No, the system does not restart an Elasticsearch cluster after you enable or disable the Public Network Access feature for the cluster. Only the status of the Public Network Access feature changes. This does not affect your cluster.

Does the system restart an Elasticsearch cluster after I reset the password used to access the cluster?

No, the system does not restart an Elasticsearch cluster after you reset the password used to access the cluster. After you reset the password for a cluster, the system only reloads the data of the cluster but does not restart the cluster. For more information, see Reset the access password for an Elasticsearch cluster.

Is the restart of an Elasticsearch cluster affected if the indexes in the cluster have no replica shards?

Yes, the restart of the cluster is affected if the indexes in an Elasticsearch cluster have no replica shards. Services may be interrupted during the restart of the cluster. In most cases, if the load of a cluster is not high and the indexes in the cluster have replica shards, the cluster can still provide services during a restart. However, access timeouts may occur during a restart in some cases. For example, if a number of nodes in the cluster are forced to restart at the same time, the cluster is heavily loaded and is not accessible, the indexes in the cluster do not have replica shards, or large amounts of data are written or queried during a restart or forced restart, access timeouts may occur. In these cases, we recommend that you design a retry mechanism on your client first and restart the cluster during off-peak hours.

How do I restart a specific type of node, such as Kibana node, or a single node?

  • Restart a specific type of node

On the Basic Information page of your Elasticsearch cluster, click Restart in the upper-right corner. In the Restart dialog box, selectNode Role for Object and select the type of node that you want to restart in the Node field. For more information, see Restart a cluster or node.

  • Restart a single node

You can use one of the following methods to restart a single node:

    • On the Basic Information page of your Elasticsearch cluster, click Restart in the upper-right corner. In the Restart dialog box, select Node for Object and select the node that you want to restart in the Node field. For more information, see Restart a cluster or node.
    • In the Node Visualization section of the Basic Information page of your Elasticsearch cluster, move the pointer over the node that you want to restart. In the popover that appears, click Restart. For more information, see View the cluster status and node information.

What do I do if the restart progress of an Elasticsearch cluster is stuck?

We recommend that you view the details of the cluster change task in the Tasks dialog box in the Elasticsearch console. For more information, see View the progress of a cluster task. The restart of an Elasticsearch cluster whose version is not V7.16 requires a few hours. If the change progress remains unchanged for a long period of time, you can refer to the instructions described in the following table to troubleshoot the issue.

Possible cause

Solution

An error occurs on a plug-in that is installed for the Elasticsearch cluster. As a result, nodes in the cluster cannot be restarted.

Delete the plug-in.

Shards cannot be allocated due to excessively high disk usage.

Delete specific indexes or temporarily set the number of replica shards to 0 for the indexes.

Shards cannot be allocated due to invalid configurations of cluster parameters.

Run the GET /_cluster/allocation/explain?pretty command to query the reason why shards are not allocated to nodes and resolve the issue based on the actual situation.

The number of replica shards is greater than the number of nodes in the Elasticsearch cluster.

Adjust the number of replica shards.

An out-of-memory (OOM) error occurs due to the excessively small specifications of the Elasticsearch cluster.

Upgrade the configuration of the Elasticsearch cluster.

Can nodes in an Elasticsearch cluster be periodically restarted?

No, the nodes in an Elasticsearch cluster cannot be periodically restarted. If you want to enable periodical restart for the nodes in your Elasticsearch cluster, you can call the RestartInstance API operation. If you call this API operation, you must also configure a scheduled task and node information.

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Data Synchronization Data Migration Alibaba Cloud Elasticsearch Cluster Restart
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