Brief Explanation
The cluster.routing.allocation.node_initial_primaries_recoveries setting in Elasticsearch controls the number of concurrent initial primary shard recoveries allowed on a single node during cluster startup or node restart. This setting helps manage the resource utilization and recovery speed when initializing primary shards.
Description
- Default Value: 4
- Possible Values: Any positive integer
- Recommendations: The default value is suitable for most scenarios. However, for nodes with high-performance hardware or in situations where faster recovery is critical, this value can be increased. Be cautious not to set it too high, as it may overwhelm the node's resources.
This setting is particularly important during cluster restarts or when new nodes join the cluster. It limits the number of primary shards that can be recovered simultaneously on a single node, helping to prevent excessive resource consumption that could potentially slow down the overall recovery process.
Example
To change this setting using the cluster settings API:
PUT _cluster/settings
{
"persistent": {
"cluster.routing.allocation.node_initial_primaries_recoveries": 6
}
}
This example increases the number of concurrent initial primary shard recoveries to 6. You might want to do this if you have powerful nodes and need to speed up the recovery process during cluster restarts. The effect will be faster initial recovery times, but potentially higher resource usage on the nodes during this process.
Common Issues or Misuses
- Setting the value too high can lead to excessive resource consumption, potentially slowing down the overall recovery process or impacting other operations.
- Setting the value too low might unnecessarily prolong the recovery process, especially in clusters with many shards or during full cluster restarts.
Do's and Don'ts
- Do monitor your cluster's performance during recovery to find the optimal setting for your hardware and shard configuration.
- Do consider adjusting this setting temporarily during planned cluster restarts for faster recovery.
- Don't set this value excessively high without considering the hardware capabilities of your nodes.
- Don't change this setting frequently; it's typically adjusted for specific scenarios or after careful performance testing.
Frequently Asked Questions
Q: How does this setting differ from cluster.routing.allocation.node_concurrent_recoveries?
A: While both settings deal with shard recoveries, cluster.routing.allocation.node_initial_primaries_recoveries specifically targets initial primary shard recoveries during node startup. cluster.routing.allocation.node_concurrent_recoveries controls the total number of concurrent recoveries per node, including replica recoveries and rebalancing.
Q: Can changing this setting impact cluster stability?
A: Yes, setting it too high can potentially impact cluster stability by overwhelming node resources. It's important to adjust this setting carefully and monitor the cluster's performance after changes.
Q: Should I adjust this setting in a production environment?
A: It's generally not recommended to change this setting in a production environment without thorough testing. Any adjustments should be made cautiously and preferably during maintenance windows.
Q: How does this setting affect cluster recovery time?
A: Increasing this value can potentially speed up cluster recovery time by allowing more primary shards to be recovered concurrently. However, the actual impact depends on your hardware capabilities and overall cluster configuration.
Q: Is this setting node-specific or cluster-wide?
A: This is a cluster-wide setting. When changed, it applies to all nodes in the cluster during their initial primary shard recovery process.
