In the cassandra. yaml file for each node, remove the IP address of the dead node from the – seeds list in the seed-provider property. If the cluster needs a new seed node to replace the dead node, add the new node’s IP address to the – seeds list of the other nodes.

How do I remove dead nodes from Cassandra cluster?

Removing a node

  1. Check whether the node is up or down using nodetool status: The nodetool command shows the status of the node (UN=up, DN=down):
  2. If the node is up, run nodetool decommission. …
  3. If the node is down, choose the appropriate option: …
  4. If removenode fails, run nodetool assassinate.

What happens when a node goes down in Cassandra?

Most node failures result from temporary conditions, such as network issues. Therefore, Cassandra assumes the node will eventually come back online, and that permanent cluster changes will be executed explicitly using nodetool .

How does Cassandra handle node failure?

If a node is down or unavailable during a write request, Cassandra handles this with the Hinted Handoff — a mechanism where the coordinator node responsible for managing a write request will store hints (write mutations) and replay it to the replica when it comes back online.

How do I restart Cassandra node?

Open a command prompt, go to the <InstallDIR>/apache-cassandra/bin directory, and run the nodetool repair -full command on one data store node in the cluster to begin populating the freshly started Cassandra nodes with all data the nodes missed during downtime.

What is Nodetool repair in Cassandra?

Repairs one or more tables. The repair command repairs one or more nodes in a cluster, and provides options for restricting repair to a set of nodes, see Repairing nodes. Performing an anti-entropy node repair on a regular basis is important, especially in an environment that deletes data frequently.

What does Nodetool rebuild do?

Rebuilds data on a node by streaming from another datacenter. Rebuilds data on a node by streaming from another datacenter. This command operates on a single node where the command is run.

How long can a Cassandra node be down?

If a Storage Node has not been able to communicate with other Storage Nodes for more than 15 days, the Storage Node assumes that its Cassandra database is stale. The Storage Node cannot rejoin the grid until Cassandra has been rebuilt using information from other Storage Nodes.

How do you check which nodes are down in Cassandra?

Check the status of the Cassandra nodes in your cluster – Go to the /<Install_Dir>/apache-cassandra/bin/ directory and type the ./nodetool status command. If the status for all the nodes shows as UN , then the nodes are up and running. If the status for any node shows as DN , then that particular node is down.

How will you check that node is alive using gossip protocol info?

You can check the state of gossip by running nodetool gossipinfo . This will show you what that node knows about via the gossip protocol.

What does Nodetool drain do?

On the Node which is going to be replaced, Run nodetool flush or nodetool drain. The difference between them is nodetool drain flushes memtables to SSTables on disk and then it stops listening for connections from the client and other nodes. The command nodetool drain is used when you want to upgrade the node.

How do I start Cassandra Datastax?

Start up commands

  1. Start the node from the installation_location .
  2. Set the type. Node/datacenter. Command. Transactional only. bin/dse cassandra. DSE Graph. bin/dse cassandra -g. DSE Analytics with Spark. bin/dse cassandra -k. DSE Search. bin/dse cassandra -s.

How do I run Cassandra as a service?

Run or Start Cassandra as Windows 10/7 or Server service

  1. Step 1: Download Apache commons daemon. …
  2. Step 2: Extract Apache commons daemon. …
  3. Step 3: Cassandra Bin folder. …
  4. Step 4: Create a Daemon folder. …
  5. Step 5: Copy prunsrv.exe. …
  6. Step 6: Install Cassandra as a Windows service.

How do I start Cassandra locally?

Steps to setup Cassandra on Window Machine locally.

  1. Cassandra need JDK to run. First need to install JDK on the PC.
  2. Go to Apache Cassandra Download Page. And Download the latest version. …
  3. Need Python2. 7 to run Cassandra Query shell cqlsh .
  4. Finally run the Cassandra Server as “cassandra.

How do I open Cassandra Cqlsh?


  1. Open Command Prompt.
  2. Navigate to the Cassandra bin directory.
  3. Type the command to start cqlsh. python cqlsh. Optionally, specify the IP address and port to start cqlsh on a different node. python cqlsh 9042.

What is Cqlsh in Cassandra?

cqlsh is a command-line interface for interacting with Cassandra using CQL (the Cassandra Query Language). It is shipped with every Cassandra package, and can be found in the bin/ directory alongside the cassandra executable.

How do I delete a keyspace in Cassandra?

To delete a keyspace using CQL

  1. Open a command shell and enter the following: cqlsh.
  2. Delete your keyspace by entering the following command at the keyspace prompt ( cqlsh: keyspace_name > ). DROP KEYSPACE IF EXISTS “myGSGKeyspace” ;
  3. Verify that your keyspace was deleted. SELECT * from system_schema. keyspaces ;

What is a keyspace in Cassandra?

In a Cassandra cluster, a keyspace is an outermost object that determines how data replicates on nodes. Keyspaces consist of core objects called column families (which are like tables in RDBMS), rows indexed by keys, data types, data center awareness, replication factor, and keyspace strategy.

Is primary key mandatory in Cassandra?

You can’t create a table in Cassandra without a primary key, But still if you want to save your data you can add an additional column to your table (let say “pk”) with data type UUID.

What is super column in Cassandra?

SuperColumn. A super column is a special column, therefore, it is also a key-value pair. But a super column stores a map of sub-columns. Generally column families are stored on disk in individual files.

What is node and cluster in Cassandra?


Node is the second layer in a cluster. This layer basically comprises of systems or computers or storage units. Each cluster may contain many nodes or systems. These systems or nodes are connected together. They collectively share data through the replication in Cassandra and independently as well.

What is a node in Cassandra?

Since it is a distributed database, Cassandra can (and usually does) have multiple nodes. A node represents a single instance of Cassandra. These nodes communicate with one another through a protocol called gossip, which is a process of computer peer-to-peer communication.

How many nodes does Cassandra cluster have?

As we said earlier, each instance of Cassandra has evolved to contain 256 virtual nodes. The Cassandra server runs core processes. For example, processes like spreading replicas around nodes or routing requests.

What is the difference between a node and cluster?

In Hadoop distributed system, Node is a single system which is responsible to store and process data. Whereas Cluster is a collection of multiple nodes which communicates with each other to perform set of operation. Multiple nodes are configured to perform a set of operations we call it Cluster.

How many nodes are in a cluster?

It’s best practice to create clusters with at least three nodes to guarantee reliability and efficiency. Every cluster has one master node, which is a unified endpoint within the cluster, and at least two worker nodes. All of these nodes communicate with each other through a shared network to perform operations.

What is rack in Cassandra?

What is a rack? A Cassandra rack is a logical grouping of Cassandra nodes within the ring. Cassandra uses racks so that it can ensure replicas are distributed among different logical groupings.