# Remove a Node from a ScyllaDB Cluster (Down Scale) You can remove nodes from your cluster to reduce its size. ## Removing a Running Node 1. Run the [nodetool status](https://docs.scylladb.com/manual/master/operating-scylla/nodetool-commands/status.md) command to check the status of the nodes in your cluster. ```console Datacenter: DC1 Status=Up/Down State=Normal/Leaving/Joining/Moving -- Address Load Tokens Owns (effective) Host ID Rack UN 192.168.1.201 112.82 KB 256 32.7% 8d5ed9f4-7764-4dbd-bad8-43fddce94b7c B1 UN 192.168.1.202 91.11 KB 256 32.9% 125ed9f4-7777-1dbn-mac8-43fddce9123e B1 UN 192.168.1.203 124.42 KB 256 32.6% 675ed9f4-6564-6dbd-ca08-43fddce952de B1 ``` 2. If the node status is **Up Normal (UN)**, run the [nodetool decommission](https://docs.scylladb.com/manual/master/operating-scylla/nodetool-commands/decommission.md) command to remove the node you are connected to. Using `nodetool decommission` is the recommended method for cluster scale-down operations. It prevents data loss by ensuring that the node you’re removing streams its data to the remaining nodes in the cluster. If the node is **Joining**, see [Safely Remove a Joining Node](https://docs.scylladb.com/manual/master/operating-scylla/procedures/cluster-management/safely-removing-joining-node.md). If the node status is **Down**, see [Removing an Unavailable Node](). #### WARNING Review current disk space utilization on existing nodes and make sure the amount of data streamed from the node being removed can fit into the disk space available on the remaining nodes. If there is not enough disk space on the remaining nodes, the removal of a node will fail. Add more storage to remaining nodes **before** starting the removal procedure. #### WARNING Removing a node in a rack may violate the [RF-rack-valid](https://docs.scylladb.com/manual/master/reference/glossary.md#term-RF-rack-valid-keyspace) constraints of some keyspace. If a keyspace uses tablets and contains a Materialized View or Secondary Index, or if the rf_rack_valid_keyspaces option is set, the invariant is enforced for the keyspace, and the node removal will be rejected if it would violate the invariant. 3. Run the `nodetool netstats` command to monitor the progress of the token reallocation. 4. Run the `nodetool status` command to verify that the node has been removed. ```console Datacenter: DC1 Status=Up/Down State=Normal/Leaving/Joining/Moving -- Address Load Tokens Owns (effective) Host ID Rack UN 192.168.1.201 112.82 KB 256 32.7% 8d5ed9f4-7764-4dbd-bad8-43fddce94b7c B1 UN 192.168.1.202 91.11 KB 256 32.9% 125ed9f4-7777-1dbn-mac8-43fddce9123e B1 ``` 5. Manually remove the data and commit log stored on that node. When a node is removed from the cluster, its data is not automatically removed. You need to manually remove the data to ensure it is no longer counted against the load on that node. Delete the data with the following commands: ```sh sudo rm -rf /var/lib/scylla/data sudo find /var/lib/scylla/commitlog -type f -delete sudo find /var/lib/scylla/hints -type f -delete sudo find /var/lib/scylla/view_hints -type f -delete ``` ## Removing an Unavailable Node If the node status is **Down Normal (DN)**, you should try to restore it. Once the node is up, use the `nodetool decommission` command (see [Removing a Running Node]()) to remove it. If all attempts to restore the node have failed and the node is **permanently down**, you can remove the node by running the `nodetool removenode` command providing the Host ID of the node you are removing. See [nodetool removenode](https://docs.scylladb.com/manual/master/operating-scylla/nodetool-commands/removenode.md) for details. #### WARNING * Using `nodetool removenode` is a fallback procedure that should only be used when a node is permanently down and cannot be recovered. * You must never use `nodetool removenode` to remove a running node that can be reached by other nodes in the cluster. **Example:** ```console nodetool removenode 675ed9f4-6564-6dbd-ca08-43fddce952de ``` The `nodetool removenode` command notifies other nodes that the token range it owns needs to be moved and the nodes should redistribute the data using streaming. Using the command does not guarantee the consistency of the rebalanced data if stream sources do not have the most recent data. In addition, if some nodes are unavailable or another error occurs, the `nodetool removenode` operation will fail. To ensure successful operation and preserve consistency among replicas, you should: * Make sure the status of all other nodes in the cluster is Up Normal (UN). If one or more nodes are unavailable, see [nodetool removenode](https://docs.scylladb.com/manual/master/operating-scylla/nodetool-commands/removenode.md) for instructions. * Run a full cluster repair **before** `nodetool removenode`, so all existing replicas have the most up-to-date data. * In the case of node failures during the `removenode` operation, re-run repair before running `nodetool removenode` (not required when [Repair Based Node Operations (RBNO)](https://docs.scylladb.com/manual/master/operating-scylla/procedures/cluster-management/repair-based-node-operation.md) for `removenode` is enabled). ### Additional Information * [Nodetool Reference](https://docs.scylladb.com/manual/master/operating-scylla/nodetool.md)