Elasticsearch FailedToCommitClusterStateException: Failed to commit cluster state

Brief Explanation

The FailedToCommitClusterStateException occurs when Elasticsearch is unable to commit changes to the cluster state. This error indicates that there's a problem with the cluster's ability to update and synchronize its internal state across nodes.

Common Causes

Network issues between cluster nodes
Disk space problems on one or more nodes
Node failures or unresponsive nodes
Misconfiguration of cluster settings
High system load or resource constraints

Troubleshooting and Resolution Steps

Check cluster health:
```
GET _cluster/health
```
Verify node status:
```
GET _cat/nodes?v
```
Inspect cluster state:
```
GET _cluster/state
```
Review Elasticsearch logs for specific error messages.
Check disk space on all nodes:
```
GET _cat/allocation?v
```
Ensure all nodes can communicate with each other by checking network connectivity.
Verify that all nodes have sufficient resources (CPU, memory, disk I/O).
Restart problematic nodes if identified.
If the issue persists, consider rolling restart of the entire cluster.
Update Elasticsearch to the latest patch version within your major version.

Additional Information and Best Practices

Regularly monitor cluster health and performance metrics.
Implement proper capacity planning to avoid resource constraints.
Use shard allocation awareness to improve cluster stability.
Keep Elasticsearch and JVM versions up to date.
Configure appropriate timeouts for cluster state updates.

Frequently Asked Questions

Q: Can this error cause data loss?
A: While not always the case, there is a potential for data loss if the cluster state cannot be updated consistently across all nodes. This emphasizes the importance of regular backups.

Q: How can I prevent this error from occurring?
A: Regular monitoring of disk space, network connectivity, and cluster health can help prevent this error. Additionally, ensuring proper cluster configuration and timely updates can reduce the risk.

Q: Is this error related to a specific Elasticsearch version?
A: This error can occur in various Elasticsearch versions. However, newer versions may have improved handling of cluster state commits. Always use the latest stable version when possible.

Q: Can I recover from this error without data loss?
A: In many cases, resolving the underlying issue (e.g., disk space, network problems) allows the cluster to recover without data loss. However, in severe cases, recovery from a recent snapshot might be necessary.

Q: How does this error affect ongoing indexing and search operations?
A: When this error occurs, it can disrupt both indexing and search operations. The cluster may become partially or fully unresponsive until the issue is resolved and the cluster state can be successfully committed.