OpenSearch An operation was attempted on a shard that is not recovering.

What is OpenSearch An operation was attempted on a shard that is not recovering.

Understanding OpenSearch

OpenSearch is a powerful, open-source search and analytics suite derived from Elasticsearch. It allows users to perform full-text search, structured search, and analytics on large volumes of data. OpenSearch is designed to be scalable, reliable, and easy to use, making it a popular choice for organizations looking to implement search and analytics capabilities.

Identifying the Symptom

When working with OpenSearch, you may encounter the IndexShardNotRecoveringException. This error typically manifests when an operation is attempted on a shard that is not in a recovering state. The error message might look something like this:

{ "error": "IndexShardNotRecoveringException", "reason": "An operation was attempted on a shard that is not recovering."}

Exploring the Issue

The IndexShardNotRecoveringException indicates that an operation was attempted on a shard that is not currently in a recovering state. Shards are the basic building blocks of an OpenSearch index, and they must be in a specific state to perform certain operations. If a shard is not recovering, it means it is not ready to accept operations that require it to be in a recovering state.

Common Causes

The shard is in an unassigned state. There is a network issue preventing the shard from recovering. Resource constraints, such as insufficient disk space or memory.

Steps to Fix the Issue

To resolve the IndexShardNotRecoveringException, follow these steps:

Step 1: Check Shard Allocation

First, verify the state of the shard using the _cat/shards API. This will help you identify if the shard is unassigned or in another state:

GET _cat/shards?v

Look for the shard in question and note its current state.

Step 2: Investigate Resource Constraints

Ensure that your cluster has sufficient resources. Check for disk space and memory usage. You can use the _cat/nodes API to get an overview of resource usage:

GET _cat/nodes?v&h=heap.percent,disk.used_percent

If resources are low, consider adding more nodes or increasing the capacity of existing nodes.

Step 3: Check Network Connectivity

Ensure that there are no network issues affecting the shard's ability to recover. Check the network configuration and logs for any connectivity issues.

Step 4: Reallocate Shards

If the shard remains unassigned, you may need to manually reallocate it. Use the _cluster/reroute API to move the shard to a different node:

POST _cluster/reroute{ "commands": [ { "allocate": { "index": "your_index", "shard": 0, "node": "target_node", "allow_primary": true } } ]}

Replace your_index and target_node with the appropriate index name and node ID.

Additional Resources

For more information on managing shards and resolving shard allocation issues, refer to the following resources:

OpenSearch Documentation _cat/shards API Cluster Reroute API