The indices.recovery.max_concurrent_file_chunks setting in Elasticsearch controls the maximum number of file chunks that can be sent concurrently during shard recovery operations. This setting plays a crucial role in optimizing the recovery process and balancing network utilization.
- Default Value: 2
- Possible Values: Positive integers
- Recommendations: The optimal value depends on your network capacity and node resources. Increasing this value can speed up recovery but may also increase network and CPU load.
This setting determines how many file chunks can be transferred simultaneously during shard recovery. A higher value can potentially speed up the recovery process, especially for large indices, but it also increases the demand on network bandwidth and node resources.
Example
To change the indices.recovery.max_concurrent_file_chunks setting using the cluster settings API:
PUT _cluster/settings
{
"persistent": {
"indices.recovery.max_concurrent_file_chunks": 5
}
}
This change would increase the number of concurrent file chunks from the default of 2 to 5. You might consider this change if you have a high-bandwidth network and powerful nodes, and you want to speed up shard recovery operations.
Common Issues and Misuses
- Setting this value too high can overwhelm network resources, potentially slowing down other cluster operations.
- Very low values may unnecessarily prolong recovery times, especially for large indices.
- Changing this setting without considering the overall cluster resources and network capacity can lead to suboptimal performance.
Do's and Don'ts
- Do monitor network utilization and recovery times when adjusting this setting.
- Do consider the size of your indices and the frequency of recovery operations when tuning this value.
- Don't set this value excessively high without ensuring your network can handle the increased load.
- Don't change this setting in isolation; consider it as part of a holistic approach to optimizing recovery performance.
- Do test changes in a non-production environment before applying them to your production cluster.
Frequently Asked Questions
Q: How does increasing indices.recovery.max_concurrent_file_chunks affect recovery speed?
A: Increasing this value can potentially speed up recovery by allowing more file chunks to be transferred simultaneously. However, the actual impact depends on your network capacity and node resources.
Q: Can setting indices.recovery.max_concurrent_file_chunks too high cause problems?
A: Yes, setting it too high can overwhelm your network and node resources, potentially slowing down other cluster operations or even causing network congestion.
Q: How do I determine the optimal value for my cluster?
A: The optimal value depends on your specific setup. Start with the default and gradually increase while monitoring recovery times and system resources. Test in a non-production environment before applying changes to production.
Q: Does this setting affect all types of recovery operations?
A: This setting affects shard recovery operations, including initial recovery when adding new nodes, recovery after node failures, and snapshot restores.
Q: How does this setting interact with other recovery-related settings?
A: This setting works in conjunction with other recovery settings like indices.recovery.max_bytes_per_sec. It's important to consider all recovery-related settings holistically when optimizing your cluster's recovery performance.
