Total number of shards for an index on a single node exceeded
Elasticsearch takes advantage of all available resources by distributing data (index shards) among the cluster nodes.
You can influence this data distribution by configuring the index.routing.allocation.total_shards_per_node dynamic index setting to restrict the maximum number of shards from a single index that can be allocated to a node.
For example, in case of a highly trafficked index, the value can be set to 1.
Various configurations limiting how many shards an index can have located on one node can lead to shards being unassigned, because the cluster does not have enough nodes to satisfy the index configuration. To fix this issue, complete the following steps:
- Check and adjust the index allocation settings to determine the current value and increase it if needed.
- Determine which data tier needs more capacity to identify the tier where shards need to be allocated.
- Resize your deployment to add capacity and accommodate additional shards.
The index.routing.allocation.total_shards_per_node setting controls the maximum number of shards that can be collocated on a node in your cluster. When this limit is reached, Elasticsearch cannot assign new shards to that node, leading to unassigned shards in your cluster.
By checking the current value and increasing it, you allow more shards to be collocated on each node, which might resolve the allocation issue without adding more capacity to your cluster.
You can run the following steps using either API console or direct Elasticsearch API calls.
Use the get index settings API to inspect the index.routing.allocation.total_shards_per_node value for the index with unassigned shards:
GET /my-index-000001/_settings/index.routing.allocation.total_shards_per_node?flat_settings
The response looks like this:
{
"my-index-000001": {
"settings": {
"index.routing.allocation.total_shards_per_node": "1"
}
}
}
- Represents the current configured value for the total number of shards that can reside on one node for the
my-index-000001index.
Use the update index settings API to increase the value for the total number of shards that can be assigned on a node to a higher value that accommodates your workload:
PUT /my-index-000001/_settings
{
"index" : {
"routing.allocation.total_shards_per_node" : "2"
}
}
- The new value for the
total_shards_per_nodeconfiguration for themy-index-000001index is increased from the previous value of1to2. Thetotal_shards_per_nodeconfiguration can also be set to-1, which represents no upper bound with regards to how many shards of the same index can reside on one node.
If increasing the index shard limit alone doesn't resolve the issue, or if you want to distribute shards more evenly, you need to identify which data tier requires additional capacity.
Use the get index settings API to retrieve the configured value for the index.routing.allocation.include._tier_preference setting:
GET /my-index-000001/_settings/index.routing.allocation.include._tier_preference?flat_settings
The response looks like this:
{
"my-index-000001": {
"settings": {
"index.routing.allocation.include._tier_preference": "data_warm,data_hot"
}
}
}
- Represents a comma-separated list of data tier node roles this index is allowed to be allocated on. The first tier in the list has the highest priority and is the tier the index is targeting. In this example, the tier preference is
data_warm,data_hot, so the index is targeting thewarmtier. If the warm tier lacks capacity, the index will fall back to thedata_hottier.
After you've identified the tier that needs more capacity, you can resize your deployment to distribute the shard load and allow previously unassigned shards to be allocated.
In ECE, resizing is limited by your allocator capacity.
To resize your deployment and increase its capacity by expanding a data tier or adding a new one, use the following options:
Option 1: Configure Autoscaling
- Log in to the Elastic Cloud console or ECE Cloud UI.
- On the home page, find your deployment and select Manage.
- Go to Actions > Edit deployment and check that autoscaling is enabled. Adjust the Enable Autoscaling for dropdown menu as needed and select Save.
- If autoscaling is successful, the cluster returns to a
healthystatus. If the cluster is still out of disk, check if autoscaling has reached its set limits and update your autoscaling settings.
Option 2: Configure deployment size and tiers
You can increase the deployment capacity by editing the deployment and adjusting the size of the existing data tiers or adding new ones.
- In Kibana, open your deployment’s navigation menu (placed under the Elastic logo in the upper left corner) and go to Manage this deployment.
- From the right hand side, click to expand the Manage dropdown button and select Edit deployment from the list of options.
- On the Edit page, increase capacity for the data tier you identified earlier by either adding a new tier with + Add capacity or adjusting the size of an existing one. Choose the desired size and availability zones for that tier.
- Navigate to the bottom of the page and click the Save button.
Option 3: Change the hardware profiles/deployment templates
You can change the hardware profile for Elastic Cloud Hosted deployments or deployment template of the Elastic Cloud Enterprise cluster to one with a higher disk-to-memory ratio.
Option 4:
Elastic Cloud Enterprise administrators can temporarily override the disk quota of Elasticsearch nodes in real time as explained in Resource overrides. We strongly recommend making this change only under the guidance of Elastic Support, and only as a temporary measure or for troubleshooting purposes.
To increase the data node capacity in your cluster, you can add more nodes to the cluster and assign the index’s target tier node role to the new nodes, or increase the disk capacity of existing nodes. Disk expansion procedures depend on your operating system and storage infrastructure and are outside the scope of Elastic support. In practice, this is often achieved by removing a node from the cluster and reinstalling it with a larger disk.
To increase the capacity of the data nodes in your Elastic Cloud on Kubernetes cluster, you can either add more data nodes to the desired tier, or increase the storage size of existing nodes.
Option 1: Add more data nodes
Update the
countfield in your data nodenodeSetsto add more nodes:apiVersion: elasticsearch.k8s.elastic.co/v1 kind: Elasticsearch metadata: name: quickstart spec: version: 9.3.0 nodeSets: - name: data-nodes count: 5 config: node.roles: ["data"] volumeClaimTemplates: - metadata: name: elasticsearch-data spec: accessModes: - ReadWriteOnce resources: requests: storage: 100Gi- Increase from previous count
Apply the changes:
kubectl apply -f your-elasticsearch-manifest.yamlECK automatically creates the new nodes with a
datanode role and Elasticsearch will relocate shards to balance the load.You can monitor the progress using:
GET /_cat/shards?v&h=state,node&s=state
Option 2: Increase storage size of existing nodes
If your storage class supports volume expansion, you can increase the storage size in the
volumeClaimTemplates:apiVersion: elasticsearch.k8s.elastic.co/v1 kind: Elasticsearch metadata: name: quickstart spec: version: 9.3.0 nodeSets: - name: data-nodes count: 3 config: node.roles: ["data"] volumeClaimTemplates: - metadata: name: elasticsearch-data spec: accessModes: - ReadWriteOnce resources: requests: storage: 200Gi- Increased from previous size
Apply the changes. If the volume driver supports
ExpandInUsePersistentVolumes, the filesystem will be resized online without restarting Elasticsearch. Otherwise, you might need to manually delete the Pods after the resize so they can be recreated with the expanded filesystem.
For more information, refer to Update your deployments and Volume claim templates > Updating the volume claim settings.
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